Write the class Calculator including: a function called addthat takes two parameters containing double values and returns their sum
a function called subtractthat takes two parameters containing double values and returns their difference (subtract the second from the first)
a function called multiply that takes two parameters containing double values and returns their product
a function called divide that takes two parameters containing double values and returns the value of the first divided by the second. If the second number is a zero, do not divide, and return "You can't divide by zero!"