presto-cli/src/main/java/io/prestosql/cli/Completion.java/Completion/commandCompleter
class Completion:    public static Completer commandCompleter()
    {
        return new StringsCompleter(ImmutableSet.<String>builder()
                .addAll(COMMANDS)
                .addAll(COMMANDS.stream()
                        .map(value -> value.toLowerCase(ENGLISH))
                        .collect(toSet()))
                .build());
    }