Write a function that takes a string containing a mathematical expression as its only parameter and breaks it into a list of tokens. Each token should be a parenthesis, an operator, or a number. (For...

Write a function that takes a string containing a mathematical expression as its only parameter and breaks it into a list of tokens. Each token should be a parenthesis, an operator, or a number. (For simplicity we will only work with integers in this problem). Return the list of tokens as the function’s only result. You may assume that the string passed to your function always contains a valid mathematical expression consisting of parentheses, operators and integers. However, your function must handle variable amounts of whitespace (including no whitespace) between these elements. Include a main program that demonstrates your tokenizing function by reading an expression from the user and printing the list of tokens. Ensure that the main program will not run when the file containing your solution is imported into another program.