code: def init_widget(self):
          
          super(AndroidRelativeLayout, self).init_widget()
          d = self.declaration
          if d.gravity:
              self.set_gravity(d.gravity)
          if d.horizontal_gravity:
              self.set_horizontal_gravity(d.horizontal_gravity)
          if d.vertical_gravity:
              self.set_vertical_gravity(d.vertical_gravity)
docs: Initialize the underlying widget.