range data type size not mention in docs.

[Jian He]

range type seem not mention their size in the docs.
multi range size is variable.
But range size seems fixed.
why it's 17 byte?

select  pg_column_size('[10,20)' ::int4range ); --17 byte
select  pg_column_size('[-2147483648,2147483647)' ::int4range ); --17 byte.