Write an ML function named parse : string -> int list that inputs the name of a text file. Your function will parse the text file character by character. The output will be a list of all the integers contained in the file. The goal of this project is to build your own parser by examining the file character by character and deciding what to do.

For example, if the text file is named input.txt and contains:

 d3%~19^fgh54 78nm,.j 1.2k~789bv

Then your function should work as follows:

 - parse("input.txt"); 

 val it = [3,~19,54,78,1,2,~789] : int list