dist/picturefill.js
function(fn) {
		var cache = {};
		return function(input) {
			if ( !(input in cache) ) {
				cache[ input ] = fn(input);
			}
			return cache[ input ];
		};
	}
function(fn) {
		var cache = {};
		return function(input) {
			if ( !(input in cache) ) {
				cache[ input ] = fn(input);
			}
			return cache[ input ];
		};
	}
function ( fn ) { var cache = { } ; return function ( input ) { if ( ! ( input in cache ) ) { cache [ input ] = fn ( input ) ; } return cache [ input ] ; } ; }
simple memoize function:
simple memoize function :