ข้อผิดพลาด tkinter/datetime/weekday/dictionary/ type : strptime() อาร์กิวเมนต์ 1 ต้องเป็น str ไม่ใช่รายการ

from tkinter import *

from datetime import datetime

root = Tk()

root.title("Moving")

root.geometry("640x480")

root.resizable(False, False)

def wky(event):

    global ab

    ab = datetime.strptime(ab, "%Y-%m-%d")

    dateDict = {0:"Mon", 1:"Tue", 2:"Wed", 3:"Thu", 4:"Fri", 5:"Sat", 6:"Sun"}

    dateDict[ab.weekday()]

    label.config(text = dateDict[ab.weekday()])

ab = Entry(root)

ab.bind("<Return>", wky)

ab.pack()

label=Label(root)

label.pack()

root.mainloop()
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python310\lib\tkinter\__init__.py", line 1921, in __call__return self.func(*args)
  File "c:\Users\JS\Desktop\PYTHONWORKSPACE\movingproject\1_name.py", line 145, in wky
    ab = datetime.strptime(ab, "%Y-%m-%d")
TypeError: strptime() argument 1 must be str, not Entry