code: def detect_colspans(self, use_actual=1):
          
          vals = self.actual_values if use_actual else self.formatted_values
          if self.is_contiguous_cols:
              for ridx in range(self.nrows):
                  for c0, c1 in span_iter(vals.iloc[ridx, :]):
                      actual_idx = self.row_ilocs[ridx]
                      self.style_cmds.append(['SPAN', (c0, actual_idx), (c1, actual_idx)])
          return self
docs: Determine if any col spans are present in the values.
          :param use_actual:  if True, check actual_values for span. if False, use the formatted_values
          :return: self