public void AlternativeParser()
{
var stream = new MemoryStream <char>("a".AsMemory());
var p1 = Combinator.Alt(Combinator.Char('x'), Combinator.Char('y'), Combinator.Char('z'));
var p2 = Combinator.Alt(Combinator.Char('a'), Combinator.Char('b'), Combinator.Char('c'));
var r1 = p1.Parse(stream);
var r2 = p2.Parse(stream);
Assert.False(r1.IsOk);
Assert.True(r2.IsOk);
Assert.Equal('a', r2.Ok.Value);
}