code: def _forward(self, x, context=None):
      x = (
          self.attn1(
              self.norm1(x),
              context=context if self.disable_self_attn else None,
          )
          + x
      )
      x = self.attn2(self.norm2(x), context=context) + x
      x = self.ff(self.norm3(x)) + x
      return x
  
imports: import math
  from inspect import isfunction
  import torch
  import torch.nn.functional
  from apex.contrib.group_norm import GroupNorm
  from einops import rearrange
  from torch import einsum, nn
  from torch._dynamo import disable
  from nemo.collections.multimodal.modules.stable_diffusion.diffusionmodules.util import checkpoint
label_desc: Use image node_id 3 for calling the BasicTransformerBlock obj's underlying member method code with example usage: obj._forward(x, context) and returns: x