Python: 2 classes importing each other causes an error?

Question

So I have the following directory setup:

• Project
  • Misc Packages and Modules
  • resources
    • shapes
      • Rectangle.py
      • Rectangle2D.py

Rectangle is just a conceptual rectangle that isn't ever drawn (using Tkinter) but is there for collision and bounds. Rectangle2D is used as a subclass to draw or fill a Rectangle. The classes before I got the error were as followed:

Rectangle.py

class Rectangle(object):
    _x = -1
    _y = -1
    _w = -1
    _h = -1

    def __init__(self, x, y, w, h):
        self._x = x
        self._y= y
        self._w = w
        self._h = h

    def intersects(self, other):
        if isinstance(other, Rectangle):
            if (self._x + self._w) > other._x > self._x and (self._y + self._h) > other._y > self._y:
                return True
            elif (self._x + self._w) > (other._x + other._w) > self._x and (self._y + self._h) > other._y > self._y:
                return True
            elif (self._x + self._w) > other._x > self._x and (other._y + other._h) > self._y > other._y:
                return True
            elif (self._x + self._w) > (other._x + other._w) > self._x and (other._y + other._h) > self._y > other._y:
                return True
            else:
                return False
        else:
            return False

    def __eq__(self, other):
        return self._x == other._x and self._y == other._y and self._w == other._w and self._h == other._h

Rectangle2D.py

from tkinter import Canvas
from .Rectangle import Rectangle

class Rectangle2D(Rectangle):
    def __init__(self, x, y, w, h):
        super(Rectangle2D, self).__init__(x, y, w, h)
        self.color = 'black'
        self.id = None

    def draw_rect(self, canvas):
        if isinstance(canvas, Canvas):
            self.id = canvas.create_rectangle(self._x, self._y, self._x + self._w, self._y + self._h, outline=self.color)
            return True
        else:
            print("Improper Parameter Type")
            return False

    def fill_rect(self, canvas):
        if isinstance(canvas, Canvas):
            self.id = canvas.create_rectangle(self._x, self._y, self._x + self._w, self._y + self._h, fill=self.color)
            return True
        else:
            print("Improper Parameter Type")
            return False

Everything was working fine until I wanted to add a method to Rectangle.py that would return a Rectangle2D.py. This record the following line to be added to Rectangle.py in addition to the method:

from .Rectangle2D import Rectangle2D

This resulted in the following error:

from .Rectangle import Rectangle
ImportError: cannot import name 'Rectangle'

What is causing this error and how do I fix it? Also note I am running Python 3.6