function wrapVisitor( clbk ) {
		return visitor;

		/**
		* Callback invoked upon encountering an AST node.
		*
		* @private
		* @param {Node} node - AST node
		* @param {Object} state - state
		* @param {Function} c - callback
		*/
		function visitor( node, state, c ) {
			var FLG = ( node !== state.ancestors[ state.ancestors.length-1 ] );
			if ( FLG ) {
				state.ancestors.push( node );
			}
			clbk( node, state, c ); // eslint-disable-line node/callback-return
			if ( FLG ) {
				state.ancestors.pop();
			}
		}
	}
Returns a visitor callback which tracks ancestor nodes.

@private
@param {Function} clbk - callback function
@returns {Function} visitor callback