def max2(x,y):
    """
    Returns: max of x, y

    This function shows the flow of if-else.

    Parameter x: first value
    Precondition: x is a number

    Parameter y: second value
    Precondition: y is a number
    """
    # Put max of x, y in z
    print('before if')          # trace
    if x > y:
        print('if x>y')         # trace
        z  = x
        print('z is '+str(z))   # watch
    else:
        print('else x<=y')      # trace
        z  = y
        print('z is '+str(z))   # watch
    print('after if')           # trace
    return z