C++ Template Function: Composing Types with 'compose'

The code defines a template function named "compose" that takes in two parameters of different types and returns their sum. The return type of the function is deduced using decltype to be the type of the sum of the two parameters.

The last line of code calls the "compose" function with the arguments 2 and 3.14. Since these arguments have different types (int and double), the template parameters T1 and T2 are deduced to be int and double respectively. The function then returns the sum of the two arguments, which in this case is 5.14.