'Extract a subset of keys from a dictionary. The filters key
will also be extracted, and each of its values will be returned
as an individual param.
:param actual_params: dict of keys to filter
:param allowed_params: list of keys that \'actual_params\' will be
reduced to
:returns: subset of \'params\' dict'

def _extract_params(self, actual_params, allowed_params):

    try:
        result = dict(actual_params.get('filters'))
    except TypeError:
        result = {}
    for allowed_param in allowed_params:
        if (allowed_param in actual_params):
            result[allowed_param] = actual_params[allowed_param]
    return result
