code: def p_switch_stmt(p):
      
  
      def backpatch(expr, stmt):
          if isinstance(stmt, node.if_stmt):
              stmt.cond_expr.args[1] = expr
              backpatch(expr, stmt.else_stmt)
  
      backpatch(p[2], p[4])
      p[0] = p[4]
docs: switch_stmt : SWITCH expr semi_opt case_list END_STMT