def one(self, default=None, as_dict=False, as_ordereddict=False):
<EOL>try:<EOL><INDENT>self[<NUM_LIT:1>]<EOL><DEDENT>except IndexError:<EOL><INDENT>return self.first(default=default, as_dict=as_dict, as_ordereddict=as_ordereddict)<EOL><DEDENT>else:<EOL><INDENT>raise ValueError('<STR_LIT>'<EOL>'<STR_LIT>'<EOL>'<STR_LIT>')<EOL><DEDENT>
Returns a single record for the RecordCollection, ensuring that it
        is the only record, or returns `default`. If `default` is an instance
        or subclass of Exception, then raise it instead of returning it.