How access to array component

Hello
How access to especific array component
of an function with return type _varchar

declaration of my function:

>>> create or replace __function( int2, int2 ) returns _varchar ....

now use the function in SQL and access to the element 1...

>>> select __function(10::int2, 20::int2)[1]
^^^ parsing error.

Thanks.

Cristian Cappo
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