Augment request parameters with includes.

    When one or all resources are requested an additional set of
    resources can be requested as part of the request. This function
    extends the given parameters for a request with a list of resource
    types passed in as a list of :class:`Resource` subclasses.

    Args:

        include([Resource class]): A list of resource classes to include

        params(dict): The (optional) dictionary of request parameters to extend

    Returns:

        An updated or new dictionary of parameters extended with an
        include query parameter.

def build_request_include(include, params):
    """Augment request parameters with includes.

    When one or all resources are requested an additional set of
    resources can be requested as part of the request. This function
    extends the given parameters for a request with a list of resource
    types passed in as a list of :class:`Resource` subclasses.

    Args:

        include([Resource class]): A list of resource classes to include

        params(dict): The (optional) dictionary of request parameters to extend

    Returns:

        An updated or new dictionary of parameters extended with an
        include query parameter.

    """
    params = params or OrderedDict()
    if include is not None:
        params['include'] = ','.join([cls._resource_type() for cls in include])
    return params