fun getNext(production: Production): ArrayList<String>{
        val s = getS()
        val result = ArrayList<String>()
        if (production.NtId == s.NtId)
            result.add(EOF)
        val productions = getAllProductionsThatContains(production.NtId!!)
        for(pro in productions){
            for(rhs in pro.RhsList){
                if(rhs.ProdPartList == null)
                    continue
                val betas = getBetas(rhs.ProdPartList!!, production.NtId!!)
                for(beta in betas){
                    if(beta == EPSILON){
                        if(pro.NtId != production.NtId){
                            val nextA = getNext(pro)
                            nextA.removeIf { it -> it == EPSILON }
                            result.addAllNonExistentElements(nextA)
                        }
                    }else{
                        if(isTerminalType(beta)){
                            result.addNonExistentElement(beta)
                        }else{
                            val firsBeta = getFirst(getProductionStatement(beta))
                            if(firsBeta.contains(EPSILON)){
                                if (pro.NtId != production.NtId!!){
                                    val nextA = getNext(pro)
                                    firsBeta.addAllNonExistentElements(nextA)
                                    firsBeta.removeIf { it -> it == EPSILON }
                                    result.addAllNonExistentElements(firsBeta)
                                }
                            }else{
                                result.addAllNonExistentElements(firsBeta)
                            }
                        }
                    }
                }
            }
        }
        return result
    }