code: def add_isoquant_data(peptides, quantpeptides, quantacc, quantfields):
      
      for peptide in base_add_isoquant_data(peptides, quantpeptides, 
                                            peptabledata.HEADER_PEPTIDE,
                                            quantacc, quantfields):
          yield peptide
docs: Runs through a peptide table and adds quant data from ANOTHER peptide 
      table that contains that data.