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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_cell_type(cell_type):
 """Get the object type of the cell by parsing the input Parameters cell_type : str or type Returns ------- cell_constructor: type The constructor of the RNNCell """

    if isinstance(cell_type, str):
        if cell_type == 'lstm':
            return rnn.LSTMCell
        elif cell_type == 'gru':
            return rnn.GRUCell
        elif cell_type == 'relu_rnn':
            return partial(rnn.RNNCell, activation='relu')
        elif cell_type == 'tanh_rnn':
            return partial(rnn.RNNCell, activation='tanh')
        else:
            raise NotImplementedError
    else:
        return cell_type