'Used to make walking animation speed be in relation to
Mario\'s x-vel'

def calculate_animation_speed(self):

    if (self.x_vel == 0):
        animation_speed = 130
    elif (self.x_vel > 0):
        animation_speed = (130 - (self.x_vel * 13))
    else:
        animation_speed = (130 - ((self.x_vel * 13) * (-1)))
    return animation_speed
