def file_hash(path, hash_type='md5'):
    """Generate a hash checksum of the contents of 'path' or None if not found.

    :param str hash_type: Any hash alrgorithm supported by :mod:`hashlib`,
                          such as md5, sha1, sha256, sha512, etc.
    """
    if os.path.exists(path):
        h = getattr(hashlib, hash_type)()
        with open(path, 'rb') as source:
            h.update(source.read())
        return h.hexdigest()
    else:
        return None
Generate a hash checksum of the contents of 'path' or None if not found.

    :param str hash_type: Any hash alrgorithm supported by :mod:`hashlib`,
                          such as md5, sha1, sha256, sha512, etc.