def codecName(encoding):
    """Return the python codec name corresponding to an encoding or None if the
    string doesn't correspond to a valid encoding."""
    if (encoding is not None and type(encoding) in types.StringTypes):
        canonicalName = ascii_punctuation_re.sub("", encoding).lower()
        return encodings.get(canonicalName, None)
    else:
        return None
Return the python codec name corresponding to an encoding or None if the
    string doesn't correspond to a valid encoding.
html5lib/inputstream.py