def node_info(node):
    """
    Returns in a list the information (value, left child value, right child
    value, parent value) for the specified node.
    """
    # Node value
    node_value = node.get_value()

    # Left node value
    left_value = None
    if (node.left is not None):
        left_value = node.left.get_value()

    # Right node value
    right_value = None
    if (node.right is not None):
        right_value = node.right.get_value()

    # Parent node value
    parent_value = None
    if (node.parent is not None):
        parent_value = node.parent.get_value()

    return [node_value, left_value, right_value, parent_value]