How to use the jwcrypto.common.json_encode function in jwcrypto

def _store_keys(keystore, usage, keys):
    name = os.path.join('kemkeys',
                        kem.KEY_USAGE_MAP[usage],
                        keys[usage]['kid'])
    keystore.set(name, json_encode(keys[usage]), True)

def f(claims, alg, lifetime=None, expires=None, not_before=None):
        """ generate token using node-jsjws """
        now = datetime.utcnow()
        return spawn(
            "fixtures.generate({now}, {header}, {claims}, {expires}, {not_before}, {key})".format(
                now=timegm(now.utctimetuple()),
                header=json_encode({'alg': alg}),
                claims=json_encode(claims),
                expires=timegm(((now + lifetime) if lifetime else expires).utctimetuple()),
                not_before=timegm((not_before or now).utctimetuple()),
                key=json_encode(base64url_decode(json_decode(key.export())['k']) if key.is_symmetric else key.export_to_pem(True, None))),
            False)
    return f

def f(sjwt, iat_skew=timedelta()):
        """ verify token using node-jsjws """
        r = spawn(
            "fixtures.verify({now}, {sjwt}, {iat_skew}, {key}, {alg})".format(
                now=timegm(datetime.utcnow().utctimetuple()),
                sjwt=json_encode(sjwt),
                iat_skew=iat_skew.total_seconds(),
                key=json_encode(base64url_decode(json_decode(key.export())['k']) if key.is_symmetric else key.export_to_pem()),
                alg=json_encode(alg)),
            True)
        return tuple(r)
    return f

def f(claims, alg, lifetime=None, expires=None, not_before=None):
        """ generate token using node-jsjws """
        now = datetime.utcnow()
        return spawn(
            "fixtures.generate({now}, {header}, {claims}, {expires}, {not_before}, {key})".format(
                now=timegm(now.utctimetuple()),
                header=json_encode({'alg': alg}),
                claims=json_encode(claims),
                expires=timegm(((now + lifetime) if lifetime else expires).utctimetuple()),
                not_before=timegm((not_before or now).utctimetuple()),
                key=json_encode(base64url_decode(json_decode(key.export())['k']) if key.is_symmetric else key.export_to_pem(True, None))),
            False)
    return f

def set(self, key, value, replace=False):
        self.protected_header = {'alg': 'dir', 'enc': self.master_enctype}
        if self.secret_protection != 'encrypt':
            self.protected_header['custodia.key'] = key
        protected = json_encode(self.protected_header)
        jwe = JWE(value, protected)
        jwe.add_recipient(self.mkey)
        cvalue = jwe.serialize(compact=True)
        return self.store.set(key, cvalue, replace)

def set(self, key, value, replace=False):
        protected = json_encode({'alg': 'dir', 'enc': self.master_enctype})
        jwe = JWE(value, protected)
        jwe.add_recipient(self.mkey)
        cvalue = jwe.serialize(compact=True)
        return super(EncryptedStore, self).set(key, cvalue, replace)

if lifetime:
        claims['exp'] = timegm((now + lifetime).utctimetuple())
    elif expires:
        claims['exp'] = timegm(expires.utctimetuple())

    if header['alg'] == 'none':
        signature = ''
    else:
        token = JWS(json_encode(claims))
        token.add_signature(priv_key, protected=header)
        signature = json_decode(token.serialize())['signature']

    return u'%s.%s.%s' % (
        base64url_encode(json_encode(header)),
        base64url_encode(json_encode(claims)),
        signature
    )