I'm trying to create a python gui for twitter that will submit my textbox as a tweet

Here is the code i'm using:

from Tkinter import *
import tweepy
from secrets import *

auth = tweepy.OAuthHandler(C_KEY, C_SECRET)
auth.set_access_token(A_TOKEN, A_TOKEN_SECRET)
api = tweepy.API(auth)

class MyFirstGUI(Frame):
    def __init__(self, master):
        Frame.__init__(self, master)
        self.grid()
        self.create_widgets()

    def create_widgets(self):
        self.instructions = Label(self, text="Enter your tweet")
        self.instructions.grid(row = 0, column = 0, columnspan = 2, sticky = W)

        self.tweet = Entry(self)
        self.tweet.grid(row=1, column = 0, sticky = W)

        self.submit_button = Button(self, text="Tweet", command = self.post)
        self.submit_button.grid(row = 2, column = 0, sticky=W)

    def post(self):
        content = self.post

        api.update_status(content)

root = Tk()
my_gui = MyFirstGUI(root)
root.mainloop()

Whenever I try tweeting, it will post something like <bound method http://MyFirstGUI.post of <__main__.MyFirstGUI instance at 0x0000000003BFF688>> instead of what I had put in the textbox. Any idea what the heck is going on?