import math

PI = math.pi


def area(radius):
    global z
    z = 6
    theArea = PI*radius**2

    return theArea


def main():
    global z

    historyOfPrompts = []
    historyOfOutput = []

    def getInput(prompt):
        x = input(prompt)
        historyOfPrompts.append(prompt)

        return x

    def showOutput(val):
        historyOfOutput.append(val)
        print(val)

    rString = getInput("Please enter the radius of a circle : ")
    r = float(rString)

    val = area(r)
    print(z)
    showOutput("The area of the circle is "+str(val))


if __name__ == "__main__":
    main()
