code: def links_to_data(self, col_name_col_num, col_val_col_num, id_a_col_num, id_b_col_num):
          
          print('Converting links to data')
          self.op_data
          unique_ids = []
          unique_vals = []
          self.op_data.append(['Name', self.ip_data[1][col_name_col_num]])
          
          for r in self.ip_data[1:]:
              if r[id_a_col_num] not in unique_ids:
                  unique_ids.append(r[id_a_col_num])
                  self.op_data.append([r[id_a_col_num], r[col_val_col_num]])
              if r[id_b_col_num] not in unique_ids:
                  unique_ids.append(r[id_b_col_num])
              if r[col_val_col_num] not in unique_vals:
                  unique_vals.append(r[col_val_col_num])
                  
          
          #for id in unique_ids:
          #    self.op_data.append([id, ''])
          
              
          print('unique_ids = ', unique_ids)
          print('unique_vals= ', unique_vals)
          print('op_data   = ', self.op_data)
          
          
          return self.op_data
docs: This is the reverse of data_to_links and takes a links table and 
          generates a data table as follows
          Input Table                         Output Table
          Cat_Name,CAT_val,Person_a,person_b  NAME,Location  
          Location,Perth,John,Fred            John,Perth
          Location,Perth,John,Cindy           Cindy,Perth
          Location,Perth,Fred,Cindy           Fred,Perth