Function smt_set 

pub fn smt_set(value: Word, key: Word, root: Word) -> SmtSetResponse

Inserts value at key in the sparse Merkle tree rooted at root, returning the prior value stored at key along with the new root. The returned SmtSetResponse contains the previous value stored under key and the updated root. Fails if the tree with the specified root does not exist in the VM’s advice provider.