public void TestParsing21() {
var g = new Grammar(new List<Production>{
CFGParser.Production("<S> → ε [45.90244483803513]"),
CFGParser.Production("<S> → <S> <S> [83.928846908234448]"),
}, Nonterminal.Of("S"));
var sentences = new List<Sentence>();
sentences.Add(Sentence.FromWords(""));
ExecuteTest(g, sentences);
}