Error language Python (trusted)

Good afternoon lists!
Somebody that it works with the Pl/Phyton language could in helping them?
We create the language python, however a common user, does not obtain to create a function using this language.
ERROR: permission denied for language plpythonu

Steps:
1º ) createlang - U postgres plpythonu DEVEL
-- however we do not obtain to give to permission
2º) GRANT ALL ON LANGUAGE plpythonu TO PUBLIC;
ERROR: language "plpythonu" is not trusted

With plpgsql we do not need to give the permission and everything functioned correctly, somebody would know in saying them as to modify the language python for TRUSTED?
Regards,
Cláudia / Carla