def node_to_tensor(node, index=0):
    """
    Get tensor name from node name and index
    Args:
        node: Name of an operation in a a graph.
        index: index of the tensor among the outputs of the node. Defautls to 0.
            When some nodes return more than one tensors, index helps to
            identify which one should be returned.

    Returns:
        A string indicating name of the required tensor
    """
    return node + ':' + str(index)