Passing a table as parameter

Hi,

Is there any way for a SQL or PL/pgSQL function to receive a table
as parameter? As an illustration, consider the dummy example below.
Note that functions get_from_data1 and get_from_data2 follow essentially
the same pattern; it would be nice to define instead a single polymorphic
function parameterised on the id and table. Is this possible?

Thanks in advance!
Jon

CREATE TABLE data1 (id int4, content text);
CREATE TABLE data2 (id int8, content text);

CREATE FUNCTION get_from_data1 (int4)
RETURNS SETOF text
LANGUAGE sql STABLE AS
$$
SELECT content FROM data1 WHERE id = $1;
$$;

CREATE FUNCTION get_from_data2 (int8)
RETURNS SETOF text
LANGUAGE sql STABLE AS
$$
SELECT content FROM data2 WHERE id = $1;
$$;