code: def expr_for_tree(self, tree, decorate=False, training=True):
      if tree.isleaf():
          raise RuntimeError("Tree structure error: meet with leaves")
      if len(tree.children) == 1:
          if not tree.children[0].isleaf():
              raise RuntimeError(
                  "Tree structure error: tree nodes with one child should be a leaf"
              )
          emb = self.E[self.w2i.get(tree.children[0].label, 0)]
          Wi, Wo, Wu = [dy.parameter(w) for w in self.WS]
          bi, bo, bu, _ = [dy.parameter(b) for b in self.BS]
          i = dy.logistic(dy.affine_transform([bi, Wi, emb]))
          o = dy.logistic(dy.affine_transform([bo, Wo, emb]))
          u = dy.tanh(dy.affine_transform([bu, Wu, emb]))
          c = dy.cmult(i, u)
          h = dy.cmult(o, dy.tanh(c))
          if decorate:
              tree._e = h
          return h, c
      if len(tree.children) != 2:
          raise RuntimeError(
              "Tree structure error: only binary trees are supported."
          )
      e1, c1 = self.expr_for_tree(tree.children[0], decorate)
      e2, c2 = self.expr_for_tree(tree.children[1], decorate)
      Ui, Uo, Uu = [dy.parameter(u) for u in self.US]
      Uf1, Uf2 = [dy.parameter(u) for u in self.UFS]
      bi, bo, bu, bf = [dy.parameter(b) for b in self.BS]
      e = dy.concatenate([e1, e2])
      i = dy.logistic(dy.affine_transform([bi, Ui, e]))
      o = dy.logistic(dy.affine_transform([bo, Uo, e]))
      f1 = dy.logistic(dy.affine_transform([bf, Uf1, e]))
      f2 = dy.logistic(dy.affine_transform([bf, Uf2, e]))
      u = dy.tanh(dy.affine_transform([bu, Uu, e]))
      c = dy.cmult(i, u) + dy.cmult(f1, c1) + dy.cmult(f2, c2)
      h = dy.cmult(o, dy.tanh(c))
      if decorate:
          tree._e = h
      return h, c
  
file_path: dynet/examples/treelstm/model.py
imports: import dynet
  import numpy
  import os
label_desc: Use image node_id 2 for calling the TreeLSTMBuilder obj's underlying member method code with example usage: obj.expr_for_tree(tree, decorate, training) and returns: h,  c, h,  c