def _make_plus_helper(obj, fields):
new_obj = {}<EOL>for key, value in obj.items():<EOL><INDENT>if key in fields or key.startswith('<STR_LIT:_>'):<EOL><INDENT>if fields.get(key):<EOL><INDENT>if isinstance(value, list):<EOL><INDENT>value = [_make_plus_helper(item, fields[key])<EOL>for item in value]<EOL><DEDENT><DEDENT>new_obj[key] = value<EOL><DEDENT>else:<EOL><INDENT>new_obj['<STR_LIT>' % key] = value<EOL><DEDENT><DEDENT>return new_obj<EOL>
add a + prefix to any fields in obj that aren't in fields