def extract_prefix(bytes_):
try:<EOL><INDENT>return varint.decode_bytes(bytes_)<EOL><DEDENT>except TypeError:<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>
Extracts the prefix from multicodec prefixed data

:param bytes bytes_: multicodec prefixed data
:return: prefix for the prefixed data
:rtype: bytes
:raises ValueError: when incorrect varint is provided