def _split_optional_netmask(address):
addr = _compat_str(address).split('<STR_LIT:/>')<EOL>if len(addr) > <NUM_LIT:2>:<EOL><INDENT>raise AddressValueError("<STR_LIT>" % address)<EOL><DEDENT>return addr<EOL>
Helper to split the netmask and raise AddressValueError if needed