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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 make_userdir(child):
 """Create a child directory."""

    userdir = os.path.dirname(child)
    if not os.path.isdir(userdir):
        if os.name == 'nt':
            # Windows forbids filenames with leading dot unless
            # a trailing dot is added.
            userdir += "."
        os.mkdir(userdir, 0700)