public ProductionRule Or(params string[] rhs)
{
if (Rhs == null)
{
throw new InvalidOperationException("Call 'Produces' before 'Or'.");
}
Rhs.Add(new ProductionRulePart());
{
foreach (var s in rhs)
{
Rhs[Rhs.Count - 1].Add(s);
}
}
return(this);
}
