def add_symmetric(self, issuer, key, usage=None):
        """
        Add a symmetric key. This is done by wrapping it in a key bundle 
        cloak since KeyJar does not handle keys directly but only through
        key bundles.
        
        :param issuer: Owner of the key
        :param key: The key 
        :param usage: What the key can be used for signing/signature 
            verification (sig) and/or encryption/decryption (enc)
        """
        if issuer not in self.issuer_keys:
            self.issuer_keys[issuer] = []

        if usage is None:
            self.issuer_keys[issuer].append(
                self.keybundle_cls([{"kty": "oct", "key": key}]))
        else:
            for use in usage:
                self.issuer_keys[issuer].append(
                    self.keybundle_cls([{"kty": "oct",
                                         "key": key,
                                         "use": use}]))
def add_symmetric ( self , issuer , key , usage = None ) : if issuer not in self . issuer_keys : self . issuer_keys [ issuer ] = [ ] if usage is None : self . issuer_keys [ issuer ] . append ( self . keybundle_cls ( [ { "kty" : "oct" , "key" : key } ] ) ) else : for use in usage : self . issuer_keys [ issuer ] . append ( self . keybundle_cls ( [ { "kty" : "oct" , "key" : key , "use" : use } ] ) )
Add a symmetric key. This is done by wrapping it in a key bundle 
        cloak since KeyJar does not handle keys directly but only through
        key bundles.
        
        :param issuer: Owner of the key
        :param key: The key 
        :param usage: What the key can be used for signing/signature 
            verification (sig) and/or encryption/decryption (enc)