torch.jit.frontend.UnsupportedNodeError: function definitions aren‘t supported

torch.jit.frontend.UnsupportedNodeError: function definitions aren't supported

 class MyModule(torch.jit.ScriptModule):
        __constants__ = ['mods']

        def __init__(self):
            super(MyModule, self).__init__()
            self.mods = torch.nn.ModuleList([SubModule() for i in range(10)])

  
   错误写法：
    @torch.jit.script_method
    def forward(self, x, targets=None):
        def _branch(_embedding, _in):
            for i, e in enumerate(_embedding):
                _in = e(_in)
                if i == 4:
                    out_branch = _in
            return _in, out_branch
        #  backbone
        x2, x1, x0 = self.backbone(x.cuda())
        #  yolo branch 0
        out0, out0_branch = _branch(s