function createCache() {
	        var keys = [];

	        function cache(key, value) {
	            // Use (key + " ") to avoid collision with native prototype properties (see Issue #157)
	            if (keys.push(key + " ") > Expr.cacheLength) {
	                // Only keep the most recent entries
	                delete cache[keys.shift()];
	            }
	            return cache[key + " "] = value;
	        }
	        return cache;
	    }
/**
	     * Create key-value caches of limited size
	     * @returns {function(string, object)} Returns the Object data after storing it on itself with
	     *	property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength)
	     *	deleting the oldest entry
	     */
Create key-value caches of limited size
@returns {function(string, object)} Returns the Object data after storing it on itself with
property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength)
deleting the oldest entry
Create key - value caches of limited size @returns { function ( string object ) } Returns the Object data after storing it on itself with property name the ( space - suffixed ) string and ( if the cache is larger than Expr . cacheLength ) deleting the oldest entry
function createCache() {
	        var keys = [];
	        function cache(key, value) {
	            if (keys.push(key + " ") > Expr.cacheLength) {
	                delete cache[keys.shift()];
	            }
	            return cache[key + " "] = value;
	        }
	        return cache;
	    }
function createCache ( ) { var keys = [ ] ; function cache ( key , value ) { if ( keys . push ( key + " " ) > Expr . cacheLength ) { delete cache [ keys . shift ( ) ] ; } return cache [ key + " " ] = value ; } return cache ; }
Create key-value caches of limited size
 @returns {function(string, object)} Returns the Object data after storing it on itself with
  property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength)
  deleting the oldest entry
Create key - value caches of limited size @returns { function ( string object ) } Returns the Object data after storing it on itself with property name the ( space - suffixed ) string and ( if the cache is larger than Expr . cacheLength ) deleting the oldest entry
// Use (key + " ") to avoid collision with native prototype properties (see Issue #157) // Only keep the most recent entries