code: public SwipeBack setDivider(Drawable drawable) {
  		mDividerDrawable = drawable;
  		mCustomDivider = drawable != null;
  		invalidate();
  		return this;
  	}
docs: Sets the drawable of the divider. You must enable the divider by calling
  {@link #setDividerEnabled(boolean)}
  
  @param drawable
  The drawable of the divider.