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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 _add_ctc_loss(pred, seq_len, num_label, loss_type):
 """ Adds CTC loss on top of pred symbol and returns the resulting symbol """

    label = mx.sym.Variable('label')
    if loss_type == 'warpctc':
        print("Using WarpCTC Loss")
        sm = _add_warp_ctc_loss(pred, seq_len, num_label, label)
    else:
        print("Using MXNet CTC Loss")
        assert loss_type == 'ctc'
        sm = _add_mxnet_ctc_loss(pred, seq_len, label)
    return sm