whole_func_string: function(url) {
  	        // TODO reuse source from script tags?
  	        if (!(url in this.sourceCache)) {
  	            this.sourceCache[url] = this.ajax(url).split('\n');
  	        }
  	        return this.sourceCache[url];
  	    }
func_code_string: function(url) {
  	        // TODO reuse source from script tags?
  	        if (!(url in this.sourceCache)) {
  	            this.sourceCache[url] = this.ajax(url).split('\n');
  	        }
  	        return this.sourceCache[url];
  	    }
func_documentation_string: Get source code from given URL if in the same domain.
  
  @param url <String> JS source URL
  @return <Array> Array of source code lines