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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def authenticate_with_serviceaccount(reactor, **kw):
 """ Create an ``IAgent`` which can issue authenticated requests to a particular Kubernetes server using a service account token. :param reactor: The reactor with which to configure the resulting agent. :param bytes path: The location of the service account directory. The default should work fine for normal use within a container. :return IAgent: An agent which will authenticate itself to a particular Kubernetes server and which will verify that server or refuse to interact with it. """

    config = KubeConfig.from_service_account(**kw)
    policy = https_policy_from_config(config)
    token = config.user["token"]
    agent = HeaderInjectingAgent(
        _to_inject=Headers({u"authorization": [u"Bearer {}".format(token)]}),
        _agent=Agent(reactor, contextFactory=policy),
    )
    return agent