Creates iterator to write to new tsv. Contains input tsv
        lines plus quant data for these.

def get_psms(self):
        """Creates iterator to write to new tsv. Contains input tsv
        lines plus quant data for these."""
        self.header = actions.create_header(self.oldheader, self.spectracol)
        self.psms = actions.generate_psms_spectradata(self.lookup, self.fn,
                                                      self.oldheader)