docs: function( editor ) {
  			if ( this._.feature )
  				return this._.feature;
  
  			var feature = this;
  
  			// If button isn't a feature, return command if is bound.
  			if ( !this.allowedContent && !this.requiredContent && this.command )
  				feature = editor.getCommand( this.command ) || feature;
  
  			return this._.feature = feature;
  		}