Build peptide table has no input file (though it has a lookup),
        which is why we set it to outfile name so the infile fetching
        and outfile creating wont error.

def parse_input(self, **kwargs):
        """Build peptide table has no input file (though it has a lookup),
        which is why we set it to outfile name so the infile fetching
        and outfile creating wont error."""
        super().parse_input(**kwargs)
        self.fn = os.path.join(os.getcwd(), 'built_peptide_table.txt')
        if self.genecentric:
            self.lookuptype = 'peptidegenecentrictable'
        elif self.noncentric:
            self.genecentric = 'plain'
            self.lookuptype = 'peptidetableplain'