Once again, we simply need to import the LineNumbers class at the top of our texteditor.py file:
from linenumbers import LineNumbers
With that taken care of, we just need to instantiate the class in our __init__ method. Since the code is already set up to apply our custom scrolling to an attribute named lne_numbers, let's delete all references to that attribute in __init__, except for the call to pack at the end, and replace them with this one line:
self.line_numbers = LineNumbers(self, self.text_area, bg="grey", fg="white", width=1)
This ensures that our custom scrolling and event bindings will still apply to this newly created class.
Give the editor another whirl and check out the new dynamic line numbers.