<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _key_backspace(self, cursor_position):

 """Action for Backspace key"""

        if self.has_selected_text():
            self.check_selection()
            self.remove_selected_text()
        elif self.current_prompt_pos == cursor_position:
            # Avoid deleting prompt
            return
        elif self.is_cursor_on_last_line():
            self.stdkey_backspace()
            if self.is_completion_widget_visible():
                # Removing only last character because if there was a selection
                # the completion widget would have been canceled
                self.completion_text = self.completion_text[:-1]