Function merklebtree::node::left_sibling

pub fn left_sibling<T>(
    node_id: i32, 
    value: &T, 
    nodes: &mut Nodes<T>
) -> (i32, i32) where
    T: PartialEq + PartialOrd + Ord + Clone + Debug + CalculateHash, 

leftSibling returns the node's left sibling and child index (in parent) if it exists, otherwise (-1,-1) key is any of keys in node (could even be deleted).