tkinter: on_cancel() method

[Rich Shepard]

I have frames for data entry and modification. Each has two buttons: Save
and Cancel. Is there a standard tkinter on_cancel() method responding to a
user clicking on the Cancel button?

My web searches find suggestions for 'after' responses, but no specific code
to close the dialog box without saving any data. Using return and close()
generate errors.

TIA,

Rich