static XPathNavigator GetFuncOverride(XPathNavigator nav, Delegate d)
{
string name = TrimName(d.Name, false);
string ext = d.Extension;
var function_override =
nav.SelectSingleNode(String.Format(Path, d.Name, ext)) ??
nav.SelectSingleNode(String.Format(Path, name, ext)) ??
nav.SelectSingleNode(String.Format(Path, Utilities.StripGL2Extension(d.Name), ext));
return(function_override);
}