Bug in documentation (trim(...))?

The following illustrates the problem (removing double quotes from a
string):

*js=# select regexp_replace(regexp_replace( '"University of Cape Town"',
'^"', ''),'"$', ''); regexp_replace
------------------------- University of Cape Town(1 row)js=# trim(both '"'
from '"University of Cape Town"');ERROR: syntax error at or near
"trim"LINE 1: trim(both '"' from '"University of Cape Town"');*

Example from the documentation:

*js=# trim(both 'xyz' from 'yxTomxx');ERROR: syntax error at or near
"trim"LINE 1: trim(both 'xyz' from 'yxTomxx'); ^*
I would think that "trim" if it works in this case would be a cheaper
function than using rexexp_replace twice.

Or is there another way?

Regards
Johann
--
Because experiencing your loyal love is better than life itself,
my lips will praise you. (Psalm 63:3)