presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitRevokeRoles
class AstBuilder:    @Override
    public Node visitRevokeRoles(SqlBaseParser.RevokeRolesContext context)
    {
        return new RevokeRoles(
                getLocation(context),
                ImmutableSet.copyOf(getIdentifiers(context.roles().identifier())),
                ImmutableSet.copyOf(getPrincipalSpecifications(context.principal())),
                context.OPTION() != null,
                getGrantorSpecificationIfPresent(context.grantor()));
    }