public void Blah()
{
var grok = new Grok();
grok.AddPattern("USERNAME", "[a-z]+");
grok.AddPattern("HENLOG", "%{USERNAME:user};");
grok.Compile("%{HENLOG:mylog}");
var match = grok.Match("aaaaa;");
match.Should().NotBeNull();
var captures = match.Captures;
}