private BnfTerm CreateTerm(GherkinTerm term, string tokens, string postFix)
{
var tokenizer = new LanguageTokenizer { Term = term, Tokens = tokens, PostFix = postFix };
var token = tokenizer.CreateIronyToken();
KeyTerms.AddRange(tokenizer.KeyTerms);
if (term == GherkinTerm.Step)
StepTerms.AddRange(tokenizer.KeyTerms);
return token;
}