code: def _get_fld2col_widths(self, **kws):
          
          fld2col_widths = self._init_fld2col_widths()
          if 'fld2col_widths' not in kws:
              return fld2col_widths
          for fld, val in kws['fld2col_widths'].items():
              fld2col_widths[fld] = val
          return fld2col_widths
docs: Return xlsx column widths based on default and user-specified field-value pairs.