class_docstr: Minimally imitate editor.EditorWindow class.
      
code: def get_selection_indices(self):
      first = self.text.index("1.0")
      last = self.text.index("end")
      return first, last
  
file_path: cpython/Lib/idlelib/idle_test/mock_idle.py
imports: from idlelib.idle_test.mock_tk import Text
label_desc: Use image node_id 2 for calling the Editor obj's underlying member method code with example usage: obj.get_selection_indices() and returns: first,  last