'Installs the extension on the editor.
:param editor: editor widget instance
:type editor: spyder.widgets.sourcecode.CodeEditor
.. note:: This method is called by editor when you install a Mode.
You should never call it yourself, even in a subclasss.
.. warning:: Don\'t forget to call **super** when subclassing'

def on_install(self, editor):

    self._editor = editor
    self.enabled = True
