class_docstr: Apply the context gate only to the source context
class_docstr_tok: ["Apply","the","context","gate","only","to","the","source","context"]
code: def forward(self, prev_emb, dec_state, attn_state):
      z, source, target = self.context_gate(
          prev_emb, dec_state, attn_state
      )
      return self.tanh(target + z * source)
  
file_path: OpenNMT-py/onmt/modules/gate.py
imports: import torch
  import torch.nn
label_desc: Use image node_id 2 for calling the SourceContextGate obj's underlying member method code with example usage: obj.forward(prev_emb, dec_state, attn_state) and returns: self