function validate( node ) {
		var cache;
		var jsdoc;
		var title;
		var tags;
		var ast;
		var i;

		jsdoc = findJSDoc( source, node );
		cache = {};
		if ( isObject( jsdoc ) ) {
			ast = parseJSDoc( jsdoc.value, DOPTS );
			tags = ast.tags;
			for ( i = 0; i < tags.length; i++ ) {
				title = tags[ i ].title;
				if ( !contains( opts.exceptions, title ) ) {
					if ( hasOwnProp( cache, title ) ) {
						report( title, jsdoc.loc );
					} else {
						cache[ title ] = true;
					}
				}
			}
		}
	}
Checks whether JSDoc comments contain JSDoc tags more than once.

@private
@param {ASTNode} node - AST node