Write a function leftA that takes an AST and returns another ASTthat is in left-associative form (likely using recursion).

type ast = | Int of int | Plus of {op1 ast; op2 ast} where the Parens constructor represents parentheses around an expression. (Parentheses are usually omitted during the act of parsing, but since we are going to change the groupings of operations as part of reassociating, it makes sense to include here.) 1 | Minus of {op1: ast; op2: ast} | Parens of ast In reassoc-src/bin/main.ml you must write a function leftAssociate astast that takes as input an AST and returns a version in which the Plus and Minus operations have been left-associated. For example, on an input tree of the form + + Your code should return the AST corresponding to 1 2 /\ 2 3 3