PyGTK calculator

I want to make a calculator with Python GTK. I am trying to get a button to display my text in the application. However, my function gives me this error TypeError: Calculator.clickedButton1() takes 1 positional argument but 2 were given. I know about self and arguments, but I have attempted a variable and passing Gtk.Entry into the function, but it doesn't work.

There was only one stackoverflow post that was similar but never solved. How do i do calculations in Python Gtk?

# this is what the application looks like simply.
import gi

gi.require_version("Gtk", "3.0")
from gi.repository import Gtk

class Calculator(Gtk.Window): # my sub class
    def __init__(self):
        super().__init__(title="Calculator") # the base class Gtk.Window
        self.set_border_width(10)

        # the header and title bar
        headerBar = Gtk.HeaderBar()
        headerBar.set_show_close_button(True)
        headerBar.props.title = "Calculator"
        self.set_titlebar(headerBar)

        # this is my button and calling the function.
        self.button1 = Gtk.Button(label="1")
        self.button1.connect("clicked", self.clickedButton1)

        # creating the entry field
        self.entry = Gtk.Entry()
        self.entry.set_text("")

        # this creates the grid
        grid = Gtk.Grid()
        grid.add(self.button1)
        grid.attach_next_to(self.entry,self.button1,Gtk.PositionType.TOP,4,4)

        self.add(grid)

    # my function
    def clickedButton1():
        self.entry.set_text("1")
        return self.entry

# creating the actual window and running continuosly.
win = Calculator()
win.connect("destroy", Gtk.main_quit)
win.show_all()
Gtk.main()

The answer is to pass self into the function. Apparently, the self is not implied like I believed. Credit goes to @mkrieger1.

    def clickedButton1(self, entry):
        text = self.entry.get_text()
        text += "1"
        self.entry.set_text(text)