if( typeof(km_scripts) == 'undefined' ) 
	var km_scripts = new Object();


function km_myclass_import(jsFile) 
{
	if( km_scripts[jsFile] != null ) 
		return;
	var scriptElt = document.createElement('script');
	scriptElt.type = 'text/javascript';
	scriptElt.src = jsFile;
	document.getElementsByTagName('head')[0].appendChild(scriptElt);
	km_scripts[jsFile] = jsFile; // or whatever value your prefer
}

//usage:
//km_myclass_import('importedfile.js');