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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def file_mtime(file_path):
 """ Returns the file modified time. This is with regards to the last modification the file has had in the droopescan repo, rather than actual file modification time in the filesystem. @param file_path: file path relative to the executable. @return datetime.datetime object. """

    if not os.path.isfile(file_path):
        raise IOError('File "%s" does not exist.' % file_path)

    ut = subprocess.check_output(['git', 'log', '-1', '--format=%ct',
        file_path]).strip()

    return datetime.fromtimestamp(int(ut))