class_docstr: ernie block class 
class_docstr_tok: ["ernie","block","class"]
docstr: forward 
docstr_tok: ["forward"]
code: def forward(
      self, inputs, attn_bias=None, past_cache=None, key_tag=None
  ):
      """forward"""
      attn_out, cache = self.attn(
          inputs,
          inputs,
          inputs,
          attn_bias,
          past_cache=past_cache,
          key_tag=key_tag,
      )  # self attention
      attn_out = self.dropout(attn_out)
      hidden = attn_out + inputs
      hidden = self.ln1(hidden)  # dropout/ add/ norm
  
      ffn_out = self.ffn(hidden)
      ffn_out = self.dropout(ffn_out)
      hidden = ffn_out + hidden
      hidden = self.ln2(hidden)
      return hidden, cache
  
imports: import logging
  import re
  import time
  import paddle
  from paddle import nn
  from paddle.nn import functional
label_desc: Use image node_id 2 for calling the ErnieBlock obj's underlying member method code with example usage: obj.forward(inputs, attn_bias, past_cache, key_tag) and returns: hidden,  cache