code: def _fmt_fields(fld_vals, fld2fmt):
      
      vals = []
      for fld, val in fld_vals:
          if fld in fld2fmt:
              val = fld2fmt[fld].format(val)
          vals.append(val)
      return vals
docs: Optional user-formatting of specific fields, eg, pval: '{:8.2e}'.