code: def append_ps_from(self, spanned_tc):
          
          source_txBody = spanned_tc.get_or_add_txBody()
          target_txBody = self.get_or_add_txBody()
  
          # ---if source is empty, there's nothing to do---
          if source_txBody.is_empty:
              return
  
          # ---a single empty paragraph in target is overwritten---
          if target_txBody.is_empty:
              target_txBody.clear_content()
  
          for p in source_txBody.p_lst:
              target_txBody.append(p)
  
          # ---neither source nor target can be left without ps---
          source_txBody.unclear_content()
          target_txBody.unclear_content()
docs: Append `a:p` elements taken from *spanned_tc*.
  
          Any non-empty paragraph elements in *spanned_tc* are removed and
          appended to the text-frame of this cell. If *spanned_tc* is left with
          no content after this process, a single empty `a:p` element is added
          to ensure the cell is compliant with the spec.