Throbbing Heart Animation with Python and Turtle (Source Code)

Animate a throbbing heart. Check out this simple heart drawing tutorial if you need help.

Source Code:

import turtle
import math

screen = turtle.Screen()
screen.title('Heart Animation - PythonTurtle.Academy')
screen.setup(1000,1000)
screen.setworldcoordinates(-1000,-1000,1000,1000)
turtle.speed(0)
turtle.hideturtle()

screen.tracer(0,0)
turtle.color('red')

def draw_heart(alpha,d):
  r = d/math.tan(math.radians(180-alpha/2))
  turtle.up()
  turtle.goto(0,-d*math.cos(math.radians(45)))
  turtle.seth(90-(alpha-180))
  turtle.down()
  turtle.begin_fill()
  turtle.fd(d)
  turtle.circle(r,alpha)
  turtle.left(180)
  turtle.circle(r,alpha)
  turtle.fd(d)
  turtle.end_fill()

a = 220
sign = -1
def animate():
  global a,sign
  turtle.clear()
  draw_heart(a,1000)
  screen.update()
  a += sign
  if a < 215:
    sign = -sign
  elif a > 220:
    sign = -sign
  screen.ontimer(animate,50)

animate()