'Get rate card
:param offer_durable_id: ID of the offer applicable for this
user account. (e.g. "0026P")
See http://azure.microsoft.com/en-us/support/legal/offer-details/
:type offer_durable_id: str
:param currency: Desired currency for the response (default: "USD")
:type currency: ``str``
:param locale: Locale (default: "en-US")
:type locale: ``str``
:param region: Region (two-letter code) (default: "US")
:type regions: ``str``
:return: A dictionary of rates whose ID\'s correspond to nothing at all
:rtype: ``dict``'

def ex_get_ratecard(self, offer_durable_id, currency='USD', locale='en-US', region='US'):

    action = ('/subscriptions/%s/providers/Microsoft.Commerce/RateCard' % (self.subscription_id,))
    params = {'api-version': '2016-08-31-preview', '$filter': ("OfferDurableId    eq    'MS-AZR-%s'    and    Currency    eq    '%s'    and    Locale    eq    '%s'    and    RegionInfo    eq    '%s'" % (offer_durable_id, currency, locale, region))}
    r = self.connection.request(action, params=params)
    return r.object
