Creates a grammar nonterminal with the given name.
@param representation the name of the nonterminal
@param index the index of the nonterminal, must be unique in
the set of all nonterminals of the grammar and
must not be greater than the number of nonterminals in the grammar
Creates a grammar nonterminal with the given name.
@param representation the name of the nonterminal @param index the index of the nonterminal, must be unique in the set of all nonterminals of the grammar and must not be greater than the number of nonterminals in the grammar