I am trying to create a function in postgresq to create a random predictable string (to use as user and password). I wrote the following code:

```
CREATE OR REPLACE FUNCTION colon.random_user_or_password(integer)
    RETURNS text AS
$BODY$
DECLARE
    letras_o_numeros TEXT[];
    letras_o_numeros_longitud INT;
    rand_user_or_pass TEXT;
    seed REAL;
BEGIN
    letras_o_numeros=array['a','b','c','d','e','f','g','h','i','j','k','l','m','o','p','q','r','s','t','u','b','w','x','y','z','A','B','C','D','E',
                           'F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','1','2','3','4','5','6','7','8','9'];
    letras_o_numeros_longitud=array_length(letras_o_numeros, 1);
    rand_user_or_pass='';
    seed=$1/power(10,ceil(log($1)));
    setseed(seed);
    WHILE char_length(rand_user_or_pass)<8 LOOP
        rand_user_or_pass=rand_user_or_pass||letras_o_numeros[ceil(random()*letras_o_numeros_longitud)];
    END LOOP;
    RETURN rand_user_or_pass;
END
$BODY$
LANGUAGE plpgsql VOLATILE
    COST 100;

```

but when I try to create the function, it gives me the following error: 
 syntax error at or near setseed(seed) in line 15. How is this function used?