func (a *ATN) NextTokensInContext(s ATNState, ctx RuleContext) *IntervalSet {
	return NewLL1Analyzer(a).Look(s, nil, ctx)
}
NextTokensInContext computes the set of valid tokens that can occur starting
in state s. If ctx is nil, the set of tokens will not include what can follow
the rule surrounding s. In other words, the set will be restricted to tokens
reachable staying within the rule of s.
package antlr
var ATNInvalidAltNumber int
type ATN struct {
	DecisionToState []DecisionState
	grammarType int
	lexerActions []LexerAction
	maxTokenType int
	modeNameToStartState map[string]*TokensStartState
	modeToStartState []*TokensStartState
	ruleToStartState []*RuleStartState
	ruleToStopState []*RuleStopState
	ruleToTokenType []int
	states []ATNState
}
func NewATN(grammarType int, maxTokenType int) *ATN {
	return &ATN{
		grammarType:          grammarType,
		maxTokenType:         maxTokenType,
		modeNameToStartState: make(map[string]*TokensStartState),
	}
}