How do you call one pltcl procedure from another?

I defined a procedure

CREATE FUNCTION meta_class (varchar) RETURNS varchar AS '
...
' LANGUAGE 'pltcl';

This works fine.  But when I want to call it from another tcl procedure I
get errors:
bf2=# CREATE FUNCTION foo (varchar) RETURNS varchar AS '
    return [meta_class $1]
' LANGUAGE 'pltcl';

bf2'# bf2'# CREATE

bf2=# bf2=# select foo(class) from weapon_Types;
ERROR:  pltcl: invalid command name "meta_class"

This IS possible -- isn't it?

-Jonathan