code: def format_field_by_match(self, value, match):
          
          groups = match.groups()
          fill, align, sign, sharp, zero, width, comma, prec, type_ = groups
          if not comma and not prec and type_ not in list('fF%'):
              return None
          if math.isnan(value) or math.isinf(value):
              return None
          locale = self.numeric_locale
          # Format number value.
          prefix = get_prefix(sign)
          if type_ == 'd':
              if prec is not None:
                  raise ValueError('precision not allowed in '
                                   'integer format specifier')
              string = format_number(value, 0, prefix, locale)
          elif type_ in 'fF%':
              format_ = format_percent if type_ == '%' else format_number
              string = format_(value, int(prec or DEFAULT_PREC), prefix, locale)
          else:
              # Don't handle otherwise.
              return None
          if not comma:
              # Formatted number always contains group symbols.
              # Remove the symbols if not required.
              string = remove_group_symbols(string, locale)
          if not (fill or align or zero or width):
              return string
          # Fix a layout.
          spec = ''.join([fill or u'', align or u'>',
                          zero or u'', width or u''])
          return format(string, spec)
docs: Formats a field by a Regex match of the format spec pattern.