gistfile1.cs

public static TResult GetFirstResult<TSource, TResult>(
IEnumerable<TSource> source, Func<TSource, TResult> invokeAction)
{

if (source== null) 
{
    throw new ArgumentNullException("source");
}

if (invokeAction== null) 
{
throw new ArgumentNullException("invokeAction");
}

return source.AsParallel().Select(item => invokeAction(item)).First();
}