Hi @kaixin, I have the a class for concatenation. I wanted to save tensors into a list so that I can use the tensors again in another connection. For example,
input - hidden1 -  hidden2 - hidden3 - out
plus hidden1 is connected to hidden3 also
x = []
x.append(operation(input, hidden1))    #list 0
x.append(operation(x[0], hidden2))    #list 1
x.append(operation(x[1], hidden3))    #list 2
x.append(operation(x[0], hidden3))    #list 3
x.append(combine(x[2], x[3]))           #list 4
x.append(operation(x[4], out))           #list 5

return x[5]