def _parse_mut(mut):
multiplier = <NUM_LIT:1><EOL>if mut.startswith("<STR_LIT:->"):<EOL><INDENT>mut = mut[<NUM_LIT:1>:]<EOL>multiplier = -<NUM_LIT:1><EOL><DEDENT>nt = mut.strip('<STR_LIT>')<EOL>pos = int(mut[:-<NUM_LIT:2>]) * multiplier<EOL>return nt, pos<EOL>
Parse mutation field to get position and nts.