title: How to bind the backspace key in tkinter to delete more than one character?
body: <p>I am wanting to create bindings that let me press tab to insert a predefined number of spaces, and then press backspace to delete that many spaces, based on a variable. </p>
  
  <p>How can I delete a pre-determined number of spaces when the user presses the backspace key? I don't know how to delete multiple characters, and when I've attempted to solve this, the binding deletes the wrong number of characters.</p>