This example defines two simple mathematical functions called addTwoInts and multiplyTwoInts.
These functions each take two Int values, and return an Int value, which is the result of
performing an appropriate mathematical operation.
The type of both of these functions is (Int, Int) -> Int. This can be read as:
“A function type that has two parameters, both of type Int, and that returns a value of
type Int.”
Here’s another example, for a function with no parameters or return value: