code: def forward(self, x):
      first_token = x[:, 0]
      pooled_output = self.fc(first_token)
      pooled_output = self.act(pooled_output)
      return pooled_output
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle.nn import ReLU, Swish, GELU
  import math
  from ppdet.core.workspace import register
  from ..shape_spec import ShapeSpec
label_desc: Use image node_id 2 for calling the BertPooler obj's underlying member method code with example usage: obj.forward(x) and returns: pooled_output