code: def forward(self, x, context=None):
      x = self.attn1(self.norm1(x)) + 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 numpy
  import paddle
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 2 for calling the BasicTransformerBlock obj's underlying member method code with example usage: obj.forward(x, context) and returns: x