求大佬们，帮我看看我的这个代码为什么最后看效果时不能显示文字呢？拜托拜托

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import turtle
import time

#  画心形圆弧
def hart_arc():
      for i in range(200):
            turtle.right(1)
            turtle.forward(2)        

def move_pen_position(x,  y):
      turtle.hideturtle()                       
      turtle.up()                              
      turtle.goto(x, y)                          
      turtle.down()                  
      turtle.showturtle()                    

love = input("请输入表白话语，默认为 ‘I Love You’：")
signature = input("请签署你的大名，不填写默认不显示：")

if love == ' ' :
    love == 'I Love You'

# 初始化
turtle.setup(width=800, height=500)
turtle.color('red', 'pink')               
turtle.pensize(3)                    
turtle.speed(1)   
# 初始化画笔起始坐标
move_pen_position(x=0, y=-180)      
turtle.left(140)                                   

turtle.begin_fill()                        

# 画心形直线  ( 左下方 ）
turtle.forward(224)         
# 画爱心圆弧
hart_arc()                     
turtle.left(120)                           
hart_arc()            
#  画心形直线   (  右下方  ）
turtle.forward(224)

turtle.end_fill()                     

#  在心形中写上表白话语
move_pen_position(0,0)   
turtle.hideturtle()         
turtle.color('blue ')