def remove_input_output_values(tree):
    """Removes all input and output values from the tree nodes.
    This is achieved by replacing every nodes input/output serialized_value with "null"
    """
    for node in tree.nodes:
        for node_input in node.inputs:
            node_input.serialized_value = "null"
        for node_output in node.outputs:
            node_output.serialized_value = "null"
    return tree