Torch fx forward

FX (Functional Transformations)
#1

model = torchvision.models.resnet18(pretrained=True)
x = torch.rand(1,3,224,224)
m = torch.fx.symbolic_trace(model)
m.layer1(x)

error:*** NotImplementedError

how to solve it.

#2 
model = torchvision.models.resnet18(pretrained=True)
x = torch.rand(1,3,224,224)
m = torch.fx.symbolic_trace(model)
m(x)
#3

why not m.layer1(x), sometimes I only use to infer part of network.