Possible children are not concatenated when forming updated semantic vector

Equation (18) of the paper shows that children are also concatenated when forming the updated semantic vector.

However, the code at this line only concatenates p_i and e_i, as far as I can tell. What about the children? Am I missing something?

Line 151 in 015e9d4

    
           tokens_output = LReLu(tf.tensordot(tf.concat([tokens_sem, tokens_output_], 2), w_comb_s, [[2], [0]]) + b_comb_s)

Thanks!
Elisa