code: def get_column_header_for_number(self, column_var_names, header=False):
          
          if not header:
              header = self.oldheader
          for col in column_var_names:
              value = getattr(self, col)
              if not value or value is None:
                  continue
              setattr(self, col, self.number_to_headerfield(value, header))
docs: This function subtracts 1 from inputted column number to comply
          with programmers counting (i.e. from 0, not from 1). For TSV data.