code: def p_stmt_list(p):
      
      if len(p) == 2:
          p[0] = node.stmt_list([p[1]] if p[1] else [])
      elif len(p) == 3:
          p[0] = p[1]
          if p[2]:
              p[0].append(p[2])
      else:
          assert 0
docs: stmt_list : stmt
                | stmt_list stmt