pub unsafe trait BinTreeContext {
    type NodeRef: Sized;

    fn getParent(&self, node: Self::NodeRef) -> Option<Self::NodeRef>;
    fn getLeftChild(&self, node: Self::NodeRef) -> Option<Self::NodeRef>;
    fn getRightChild(&self, node: Self::NodeRef) -> Option<Self::NodeRef>;

    fn setParent(&mut self, node: Self::NodeRef, newParent: Option<Self::NodeRef>);
    fn setLeftChild(&mut self, node: Self::NodeRef, newChild: Option<Self::NodeRef>);
    fn setRightChild(&mut self, node: Self::NodeRef, newChild: Option<Self::NodeRef>);
}