def get_api_access_token(handler_input):
    """Return the api access token in the request.

    The method retrieves the ``apiAccessToken`` from the input request,
    which has the encapsulated information of permissions granted by the
    user. This token can be used to call Alexa-specific APIs. More information
    about this can be found here :
    https://developer.amazon.com/docs/custom-skills/request-and-response-json-reference.html#system-object

    The SDK already includes this token in the API calls done through the
    `service_client_factory` in
    :py:class:`ask_sdk_core.handler_input.HandlerInput`.

    :param handler_input: The handler input instance that is generally
        passed in the sdk's request and exception components
    :type handler_input: ask_sdk_core.handler_input.HandlerInput
    :return: Api access token from the input request, which encapsulates any
        permissions consented by the user
    :rtype: str
    """
    return handler_input.request_envelope.context.system.api_access_token
