def _warning(code):
if isinstance(code, str):<EOL><INDENT>return code<EOL><DEDENT>message = '<STR_LIT>'<EOL>if isinstance(code, tuple):<EOL><INDENT>if isinstance(code[<NUM_LIT:0>], str):<EOL><INDENT>message = code[<NUM_LIT:1>]<EOL>code = code[<NUM_LIT:0>]<EOL><DEDENT><DEDENT>return CFG_BIBRECORD_WARNING_MSGS.get(code, '<STR_LIT>') + message<EOL>
Return a warning message of code 'code'.

If code = (cd, str) it returns the warning message of code 'cd' and appends
str at the end