presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitCreateTable
class AstBuilder:    @Override
    public Node visitCreateTable(SqlBaseParser.CreateTableContext context)
    {
        Optional<String> comment = Optional.empty();
        if (context.COMMENT() != null) {
            comment = Optional.of(((StringLiteral) visit(context.string())).getValue());
        }
        List<Property> properties = ImmutableList.of();
        if (context.properties() != null) {
            properties = visit(context.properties().property(), Property.class);
        }
        return new CreateTable(
                getLocation(context),
                getQualifiedName(context.qualifiedName()),
                visit(context.tableElement(), TableElement.class),
                context.EXISTS() != null,
                properties,
                comment);
    }