g Write a Python program to calculate the perimeter and area of a circle: 1) create a global constant PI and assign the fixed value 3.14 to it (it must be used for calculations in the program). 2) create a global variable radius, and asks the user to enter an initial value for it. 3) define a function named cal_perimeter which has no parameter. This function calculates and prints out the perimeter of the circle using the following formula. formula: circle's perimeter