def _del_ins_lengths(self, ilen):
if self.ref == self.alt:<EOL><INDENT>del_len = ins_len = <NUM_LIT:0><EOL><DEDENT>else:<EOL><INDENT>del_len = <NUM_LIT:0> if self.ref is None else ilen<EOL>ins_len = <NUM_LIT:0> if self.alt is None else len(self.alt)<EOL><DEDENT>return (del_len, ins_len)<EOL>
returns (del_len, ins_len).
        Unspecified ref or alt returns None for del_len or ins_len respectively.