Please do not share your code on the forum. That’s not allowed by the Code of Conduct.
Try removing the “inputs =” part of that statement, see if that helps.
If not, then do a forum search for “multiple inbound nodes”. This is a fairly common issue in this assignment.
Tip: Since the LSTM_cell is a global object within the notebook, every time you make a change to one of functions that modify or use LSTM_cell during debugging, you need to restart the kernel and run all of the cells again. Otherwise your code gets out-of-sync with the state of the LSTM_cell object.