X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=file_utils.py;h=7a64f9f3eef7f8073736863bc87d408db8f49695;hb=a9bdfd8fc9f84b7b2c09a57cd12ba32259e84d1c;hp=7108d6a0db74842a74587e8f9c53a1973fb0bde8;hpb=3bc4daf1edc121cd633429187392227f2fa61885;p=python_utils.git

diff --git a/file_utils.py b/file_utils.py
index 7108d6a..7a64f9f 100644
--- a/file_utils.py
+++ b/file_utils.py
@@ -1,28 +1,274 @@
 #!/usr/bin/env python3
 
+# © Copyright 2021-2022, Scott Gasch
+
 """Utilities for working with files."""
 
+import contextlib
 import datetime
 import errno
+import glob
 import hashlib
 import logging
 import os
+import pathlib
+import re
 import time
-from typing import Optional
-import glob
-from os.path import isfile, join, exists
+from os.path import exists, isfile, join
+from typing import Callable, List, Literal, Optional, TextIO
+from uuid import uuid4
 
-import datetime_utils
+logger = logging.getLogger(__name__)
 
 
-logger = logging.getLogger(__name__)
+def remove_newlines(x: str) -> str:
+    """Trivial function to be used as a line_transformer in
+    :meth:`slurp_file` for no newlines in file contents"""
+    return x.replace('\n', '')
+
+
+def strip_whitespace(x: str) -> str:
+    """Trivial function to be used as a line_transformer in
+    :meth:`slurp_file` for no leading / trailing whitespace in
+    file contents"""
+    return x.strip()
+
+
+def remove_hash_comments(x: str) -> str:
+    """Trivial function to be used as a line_transformer in
+    :meth:`slurp_file` for no # comments in file contents"""
+    return re.sub(r'#.*$', '', x)
+
+
+def slurp_file(
+    filename: str,
+    *,
+    skip_blank_lines=False,
+    line_transformers: Optional[List[Callable[[str], str]]] = None,
+):
+    """Reads in a file's contents line-by-line to a memory buffer applying
+    each line transformation in turn.
+
+    Args:
+        filename: file to be read
+        skip_blank_lines: should reading skip blank lines?
+        line_transformers: little string->string transformations
+    """
+
+    ret = []
+    xforms = []
+    if line_transformers is not None:
+        for x in line_transformers:
+            xforms.append(x)
+    if not file_is_readable(filename):
+        raise Exception(f'{filename} can\'t be read.')
+    with open(filename) as rf:
+        for line in rf:
+            for transformation in xforms:
+                line = transformation(line)
+            if skip_blank_lines and line == '':
+                continue
+            ret.append(line)
+    return ret
+
+
+def remove(path: str) -> None:
+    """Deletes a file.  Raises if path refers to a directory or a file
+    that doesn't exist.
+
+    Args:
+        path: the path of the file to delete
+
+    >>> import os
+    >>> filename = '/tmp/file_utils_test_file'
+    >>> os.system(f'touch {filename}')
+    0
+    >>> does_file_exist(filename)
+    True
+    >>> remove(filename)
+    >>> does_file_exist(filename)
+    False
+    """
+    os.remove(path)
+
+
+def delete(path: str) -> None:
+    """This is a convenience for my dumb ass who can't remember os.remove
+    sometimes.
+    """
+    os.remove(path)
+
+
+def without_extension(path: str) -> str:
+    """Remove one (the last) extension from a file or path.
+
+    Args:
+        path: the path from which to remove an extension
+
+    Returns:
+        the path with one extension removed.
+
+    >>> without_extension('foobar.txt')
+    'foobar'
+
+    >>> without_extension('/home/scott/frapp.py')
+    '/home/scott/frapp'
+
+    >>> f = 'a.b.c.tar.gz'
+    >>> while('.' in f):
+    ...     f = without_extension(f)
+    ...     print(f)
+    a.b.c.tar
+    a.b.c
+    a.b
+    a
+
+    >>> without_extension('foobar')
+    'foobar'
+
+    """
+    return os.path.splitext(path)[0]
+
+
+def without_all_extensions(path: str) -> str:
+    """Removes all extensions from a path; handles multiple extensions
+    like foobar.tar.gz -> foobar.
+
+    Args:
+        path: the path from which to remove all extensions
+
+    Returns:
+        the path with all extensions removed.
+
+    >>> without_all_extensions('/home/scott/foobar.1.tar.gz')
+    '/home/scott/foobar'
+
+    """
+    while '.' in path:
+        path = without_extension(path)
+    return path
+
+
+def get_extension(path: str) -> str:
+    """Extract and return one (the last) extension from a file or path.
+
+    Args:
+        path: the path from which to extract an extension
+
+    Returns:
+        The last extension from the file path.
+
+    >>> get_extension('this_is_a_test.txt')
+    '.txt'
+
+    >>> get_extension('/home/scott/test.py')
+    '.py'
+
+    >>> get_extension('foobar')
+    ''
+
+    """
+    return os.path.splitext(path)[1]
+
+
+def get_all_extensions(path: str) -> List[str]:
+    """Return the extensions of a file or path in order.
+
+    Args:
+        path: the path from which to extract all extensions.
+
+    Returns:
+        a list containing each extension which may be empty.
+
+    >>> get_all_extensions('/home/scott/foo.tar.gz.1')
+    ['.tar', '.gz', '.1']
+
+    >>> get_all_extensions('/home/scott/foobar')
+    []
+
+    """
+    ret = []
+    while True:
+        ext = get_extension(path)
+        path = without_extension(path)
+        if ext:
+            ret.append(ext)
+        else:
+            ret.reverse()
+            return ret
+
+
+def without_path(filespec: str) -> str:
+    """Returns the base filename without any leading path.
+
+    Args:
+        filespec: path to remove leading directories from
 
+    Returns:
+        filespec without leading dir components.
+
+    >>> without_path('/home/scott/foo.py')
+    'foo.py'
+
+    >>> without_path('foo.py')
+    'foo.py'
+
+    """
+    return os.path.split(filespec)[1]
+
+
+def get_path(filespec: str) -> str:
+    """Returns just the path of the filespec by removing the filename and
+    extension.
+
+    Args:
+        filespec: path to remove filename / extension(s) from
+
+    Returns:
+        filespec with just the leading directory components and no
+            filename or extension(s)
+
+    >>> get_path('/home/scott/foobar.py')
+    '/home/scott'
+
+    >>> get_path('/home/scott/test.1.2.3.gz')
+    '/home/scott'
+
+    >>> get_path('~scott/frapp.txt')
+    '~scott'
 
-def create_path_if_not_exist(path, on_error=None):
     """
-    Attempts to create path if it does not exist. If on_error is
-    specified, it is called with an exception if one occurs, otherwise
-    exception is rethrown.
+    return os.path.split(filespec)[0]
+
+
+def get_canonical_path(filespec: str) -> str:
+    """Returns a canonicalized absolute path.
+
+    Args:
+        filespec: the path to canonicalize
+
+    Returns:
+        the canonicalized path
+
+    >>> get_canonical_path('/home/scott/../../home/lynn/../scott/foo.txt')
+    '/usr/home/scott/foo.txt'
+
+    """
+    return os.path.realpath(filespec)
+
+
+def create_path_if_not_exist(path, on_error=None) -> None:
+    """
+    Attempts to create path if it does not exist already.
+
+    .. warning::
+
+        Files are created with mode 0x0777 (i.e. world read/writeable).
+
+    Args:
+        path: the path to attempt to create
+        on_error: If True, it's invoked on error conditions.  Otherwise
+            any exceptions are raised.
 
     >>> import uuid
     >>> import os
@@ -33,7 +279,7 @@ def create_path_if_not_exist(path, on_error=None):
     >>> os.path.exists(path)
     True
     """
-    logger.debug(f"Creating path {path}")
+    logger.debug("Creating path %s", path)
     previous_umask = os.umask(0)
     try:
         os.makedirs(path)
@@ -49,38 +295,133 @@ def create_path_if_not_exist(path, on_error=None):
 
 
 def does_file_exist(filename: str) -> bool:
+    """Returns True if a file exists and is a normal file.
+
+    Args:
+        filename: filename to check
+
+    Returns:
+        True if filename exists and is a normal file.
+
+    >>> does_file_exist(__file__)
+    True
+    >>> does_file_exist('/tmp/2492043r9203r9230r9230r49230r42390r4230')
+    False
+    """
     return os.path.exists(filename) and os.path.isfile(filename)
 
 
+def file_is_readable(filename: str) -> bool:
+    """True if file exists, is a normal file and is readable by the
+    current process.  False otherwise.
+
+    Args:
+        filename: the filename to check for read access
+    """
+    return does_file_exist(filename) and os.access(filename, os.R_OK)
+
+
+def file_is_writable(filename: str) -> bool:
+    """True if file exists, is a normal file and is writable by the
+    current process.  False otherwise.
+
+    Args:
+        filename: the file to check for write access.
+    """
+    return does_file_exist(filename) and os.access(filename, os.W_OK)
+
+
+def file_is_executable(filename: str) -> bool:
+    """True if file exists, is a normal file and is executable by the
+    current process.  False otherwise.
+
+    Args:
+        filename: the file to check for execute access.
+    """
+    return does_file_exist(filename) and os.access(filename, os.X_OK)
+
+
 def does_directory_exist(dirname: str) -> bool:
+    """Returns True if a file exists and is a directory.
+
+    >>> does_directory_exist('/tmp')
+    True
+    >>> does_directory_exist('/xyzq/21341')
+    False
+    """
     return os.path.exists(dirname) and os.path.isdir(dirname)
 
 
 def does_path_exist(pathname: str) -> bool:
+    """Just a more verbose wrapper around os.path.exists."""
     return os.path.exists(pathname)
 
 
 def get_file_size(filename: str) -> int:
+    """Returns the size of a file in bytes.
+
+    Args:
+        filename: the filename to size
+
+    Returns:
+        size of filename in bytes
+    """
     return os.path.getsize(filename)
 
 
 def is_normal_file(filename: str) -> bool:
+    """Returns True if filename is a normal file.
+
+    >>> is_normal_file(__file__)
+    True
+    """
     return os.path.isfile(filename)
 
 
 def is_directory(filename: str) -> bool:
+    """Returns True if filename is a directory.
+
+    >>> is_directory('/tmp')
+    True
+    """
     return os.path.isdir(filename)
 
 
 def is_symlink(filename: str) -> bool:
+    """True if filename is a symlink, False otherwise.
+
+    >>> is_symlink('/tmp')
+    False
+
+    >>> is_symlink('/home')
+    True
+
+    """
     return os.path.islink(filename)
 
 
 def is_same_file(file1: str, file2: str) -> bool:
+    """Returns True if the two files are the same inode.
+
+    >>> is_same_file('/tmp', '/tmp/../tmp')
+    True
+
+    >>> is_same_file('/tmp', '/home')
+    False
+
+    """
     return os.path.samefile(file1, file2)
 
 
 def get_file_raw_timestamps(filename: str) -> Optional[os.stat_result]:
+    """Stats the file and returns an os.stat_result or None on error.
+
+    Args:
+        filename: the file whose timestamps to fetch
+
+    Returns:
+        the os.stat_result or None to indicate an error occurred
+    """
     try:
         return os.stat(filename)
     except Exception as e:
@@ -88,7 +429,23 @@ def get_file_raw_timestamps(filename: str) -> Optional[os.stat_result]:
         return None
 
 
-def get_file_raw_timestamp(filename: str, extractor) -> Optional[float]:
+def get_file_raw_timestamp(
+    filename: str, extractor: Callable[[os.stat_result], Optional[float]]
+) -> Optional[float]:
+    """Stat a file and, if successful, use extractor to fetch some
+    subset of the information in the os.stat_result.  See also
+    :meth:`get_file_raw_atime`, :meth:`get_file_raw_mtime`, and
+    :meth:`get_file_raw_ctime` which just call this with a lambda
+    extractor.
+
+    Args:
+        filename: the filename to stat
+        extractor: Callable that takes a os.stat_result and produces
+            something useful(?) with it.
+
+    Returns:
+        whatever the extractor produced or None on error.
+    """
     tss = get_file_raw_timestamps(filename)
     if tss is not None:
         return extractor(tss)
@@ -96,18 +453,44 @@ def get_file_raw_timestamp(filename: str, extractor) -> Optional[float]:
 
 
 def get_file_raw_atime(filename: str) -> Optional[float]:
+    """Get a file's raw access time or None on error.
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    and :meth:`get_file_atime_age_seconds`.
+    """
     return get_file_raw_timestamp(filename, lambda x: x.st_atime)
 
 
 def get_file_raw_mtime(filename: str) -> Optional[float]:
+    """Get a file's raw modification time or None on error.
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    and :meth:`get_file_mtime_age_seconds`.
+    """
     return get_file_raw_timestamp(filename, lambda x: x.st_mtime)
 
 
 def get_file_raw_ctime(filename: str) -> Optional[float]:
+    """Get a file's raw creation time or None on error.
+
+    See also :meth:`get_file_ctime_as_datetime`,
+    :meth:`get_file_ctime_timedelta`,
+    and :meth:`get_file_ctime_age_seconds`.
+    """
     return get_file_raw_timestamp(filename, lambda x: x.st_ctime)
 
 
 def get_file_md5(filename: str) -> str:
+    """Hashes filename's disk contents and returns the MD5 digest.
+
+    Args:
+        filename: the file whose contents to hash
+
+    Returns:
+        the MD5 digest of the file's contents.  Raises on errors.
+    """
     file_hash = hashlib.md5()
     with open(filename, "rb") as f:
         chunk = f.read(8192)
@@ -118,25 +501,47 @@ def get_file_md5(filename: str) -> str:
 
 
 def set_file_raw_atime(filename: str, atime: float):
+    """Sets a file's raw access time.
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    :meth:`get_file_atime_age_seconds`,
+    and :meth:`get_file_raw_atime`.
+    """
     mtime = get_file_raw_mtime(filename)
+    assert mtime is not None
     os.utime(filename, (atime, mtime))
 
 
 def set_file_raw_mtime(filename: str, mtime: float):
+    """Sets a file's raw modification time.
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    :meth:`get_file_mtime_age_seconds`,
+    and :meth:`get_file_raw_mtime`.
+    """
     atime = get_file_raw_atime(filename)
+    assert atime is not None
     os.utime(filename, (atime, mtime))
 
 
 def set_file_raw_atime_and_mtime(filename: str, ts: float = None):
+    """Sets both a file's raw modification and access times
+
+    Args:
+        filename: the file whose times to set
+        ts: the raw time to set or None to indicate time should be
+            set to the current time.
+    """
     if ts is not None:
         os.utime(filename, (ts, ts))
     else:
         os.utime(filename, None)
 
 
-def convert_file_timestamp_to_datetime(
-    filename: str, producer
-) -> Optional[datetime.datetime]:
+def convert_file_timestamp_to_datetime(filename: str, producer) -> Optional[datetime.datetime]:
+    """Convert a raw file timestamp into a python datetime."""
     ts = producer(filename)
     if ts is not None:
         return datetime.datetime.fromtimestamp(ts)
@@ -144,18 +549,41 @@ def convert_file_timestamp_to_datetime(
 
 
 def get_file_atime_as_datetime(filename: str) -> Optional[datetime.datetime]:
+    """Fetch a file's access time as a python datetime.
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    :meth:`get_file_atime_age_seconds`,
+    :meth:`describe_file_atime`,
+    and :meth:`get_file_raw_atime`.
+    """
     return convert_file_timestamp_to_datetime(filename, get_file_raw_atime)
 
 
 def get_file_mtime_as_datetime(filename: str) -> Optional[datetime.datetime]:
+    """Fetches a file's modification time as a python datetime.
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    :meth:`get_file_mtime_age_seconds`,
+    and :meth:`get_file_raw_mtime`.
+    """
     return convert_file_timestamp_to_datetime(filename, get_file_raw_mtime)
 
 
 def get_file_ctime_as_datetime(filename: str) -> Optional[datetime.datetime]:
+    """Fetches a file's creation time as a python datetime.
+
+    See also :meth:`get_file_ctime_as_datetime`,
+    :meth:`get_file_ctime_timedelta`,
+    :meth:`get_file_ctime_age_seconds`,
+    and :meth:`get_file_raw_ctime`.
+    """
     return convert_file_timestamp_to_datetime(filename, get_file_raw_ctime)
 
 
 def get_file_timestamp_age_seconds(filename: str, extractor) -> Optional[int]:
+    """~Internal helper"""
     now = time.time()
     ts = get_file_raw_timestamps(filename)
     if ts is None:
@@ -165,20 +593,41 @@ def get_file_timestamp_age_seconds(filename: str, extractor) -> Optional[int]:
 
 
 def get_file_atime_age_seconds(filename: str) -> Optional[int]:
+    """Gets a file's access time as an age in seconds (ago).
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    :meth:`get_file_atime_age_seconds`,
+    :meth:`describe_file_atime`,
+    and :meth:`get_file_raw_atime`.
+    """
     return get_file_timestamp_age_seconds(filename, lambda x: x.st_atime)
 
 
 def get_file_ctime_age_seconds(filename: str) -> Optional[int]:
+    """Gets a file's creation time as an age in seconds (ago).
+
+    See also :meth:`get_file_ctime_as_datetime`,
+    :meth:`get_file_ctime_timedelta`,
+    :meth:`get_file_ctime_age_seconds`,
+    and :meth:`get_file_raw_ctime`.
+    """
     return get_file_timestamp_age_seconds(filename, lambda x: x.st_ctime)
 
 
 def get_file_mtime_age_seconds(filename: str) -> Optional[int]:
+    """Gets a file's modification time as seconds (ago).
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    :meth:`get_file_mtime_age_seconds`,
+    and :meth:`get_file_raw_mtime`.
+    """
     return get_file_timestamp_age_seconds(filename, lambda x: x.st_mtime)
 
 
-def get_file_timestamp_timedelta(
-    filename: str, extractor
-) -> Optional[datetime.timedelta]:
+def get_file_timestamp_timedelta(filename: str, extractor) -> Optional[datetime.timedelta]:
+    """~Internal helper"""
     age = get_file_timestamp_age_seconds(filename, extractor)
     if age is not None:
         return datetime.timedelta(seconds=float(age))
@@ -186,47 +635,109 @@ def get_file_timestamp_timedelta(
 
 
 def get_file_atime_timedelta(filename: str) -> Optional[datetime.timedelta]:
+    """How long ago was a file accessed as a timedelta?
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    :meth:`get_file_atime_age_seconds`,
+    :meth:`describe_file_atime`,
+    and :meth:`get_file_raw_atime`.
+    """
     return get_file_timestamp_timedelta(filename, lambda x: x.st_atime)
 
 
 def get_file_ctime_timedelta(filename: str) -> Optional[datetime.timedelta]:
+    """How long ago was a file created as a timedelta?
+
+    See also :meth:`get_file_ctime_as_datetime`,
+    :meth:`get_file_ctime_timedelta`,
+    :meth:`get_file_ctime_age_seconds`,
+    and :meth:`get_file_raw_ctime`.
+    """
     return get_file_timestamp_timedelta(filename, lambda x: x.st_ctime)
 
 
 def get_file_mtime_timedelta(filename: str) -> Optional[datetime.timedelta]:
+    """
+    Gets a file's modification time as a python timedelta.
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    :meth:`get_file_mtime_age_seconds`,
+    and :meth:`get_file_raw_mtime`.
+    """
     return get_file_timestamp_timedelta(filename, lambda x: x.st_mtime)
 
 
-def describe_file_timestamp(
-    filename: str, extractor, *, brief=False
-) -> Optional[str]:
+def describe_file_timestamp(filename: str, extractor, *, brief=False) -> Optional[str]:
+    """~Internal helper"""
+    from datetime_utils import describe_duration, describe_duration_briefly
+
     age = get_file_timestamp_age_seconds(filename, extractor)
     if age is None:
         return None
     if brief:
-        return datetime_utils.describe_duration_briefly(age)
+        return describe_duration_briefly(age)
     else:
-        return datetime_utils.describe_duration(age)
+        return describe_duration(age)
 
 
 def describe_file_atime(filename: str, *, brief=False) -> Optional[str]:
+    """
+    Describe how long ago a file was accessed.
+
+    See also :meth:`get_file_atime_as_datetime`,
+    :meth:`get_file_atime_timedelta`,
+    :meth:`get_file_atime_age_seconds`,
+    :meth:`describe_file_atime`,
+    and :meth:`get_file_raw_atime`.
+    """
     return describe_file_timestamp(filename, lambda x: x.st_atime, brief=brief)
 
 
 def describe_file_ctime(filename: str, *, brief=False) -> Optional[str]:
+    """Describes a file's creation time.
+
+    See also :meth:`get_file_ctime_as_datetime`,
+    :meth:`get_file_ctime_timedelta`,
+    :meth:`get_file_ctime_age_seconds`,
+    and :meth:`get_file_raw_ctime`.
+    """
     return describe_file_timestamp(filename, lambda x: x.st_ctime, brief=brief)
 
 
 def describe_file_mtime(filename: str, *, brief=False) -> Optional[str]:
+    """
+    Describes how long ago a file was modified.
+
+    See also :meth:`get_file_mtime_as_datetime`,
+    :meth:`get_file_mtime_timedelta`,
+    :meth:`get_file_mtime_age_seconds`,
+    and :meth:`get_file_raw_mtime`.
+    """
     return describe_file_timestamp(filename, lambda x: x.st_mtime, brief=brief)
 
 
+def touch_file(filename: str, *, mode: Optional[int] = 0o666):
+    """Like unix "touch" command's semantics: update the timestamp
+    of a file to the current time if the file exists.  Create the
+    file if it doesn't exist.
+
+    Args:
+        filename: the filename
+        mode: the mode to create the file with
+    """
+    pathlib.Path(filename, mode=mode).touch()
+
+
 def expand_globs(in_filename: str):
+    """Expands shell globs (* and ? wildcards) to the matching files."""
     for filename in glob.glob(in_filename):
         yield filename
 
 
 def get_files(directory: str):
+    """Returns the files in a directory as a generator."""
     for filename in os.listdir(directory):
         full_path = join(directory, filename)
         if isfile(full_path) and exists(full_path):
@@ -234,6 +745,7 @@ def get_files(directory: str):
 
 
 def get_directories(directory: str):
+    """Returns the subdirectories in a directory as a generator."""
     for d in os.listdir(directory):
         full_path = join(directory, d)
         if not isfile(full_path) and exists(full_path):
@@ -241,8 +753,41 @@ def get_directories(directory: str):
 
 
 def get_files_recursive(directory: str):
+    """Find the files and directories under a root recursively."""
     for filename in get_files(directory):
         yield filename
     for subdir in get_directories(directory):
         for file_or_directory in get_files_recursive(subdir):
             yield file_or_directory
+
+
+class FileWriter(contextlib.AbstractContextManager):
+    """A helper that writes a file to a temporary location and then moves
+    it atomically to its ultimate destination on close.
+    """
+
+    def __init__(self, filename: str) -> None:
+        self.filename = filename
+        uuid = uuid4()
+        self.tempfile = f'{filename}-{uuid}.tmp'
+        self.handle: Optional[TextIO] = None
+
+    def __enter__(self) -> TextIO:
+        assert not does_path_exist(self.tempfile)
+        self.handle = open(self.tempfile, mode="w")
+        return self.handle
+
+    def __exit__(self, exc_type, exc_val, exc_tb) -> Literal[False]:
+        if self.handle is not None:
+            self.handle.close()
+            cmd = f'/bin/mv -f {self.tempfile} {self.filename}'
+            ret = os.system(cmd)
+            if (ret >> 8) != 0:
+                raise Exception(f'{cmd} failed, exit value {ret>>8}!')
+        return False
+
+
+if __name__ == '__main__':
+    import doctest
+
+    doctest.testmod()