code: def p_fromitem_list(self,t):
      
      if len(t)==2: t[0] = [t[1]]
      elif len(t)==4: t[0] = t[1] + [t[3]]
      else: raise NotImplementedError('unk_len', len(t)) # pragma: no cover
docs: fromitem_list : fromitem_list ',' fromitem
                       | fromitem