code: def _get_crl_url(self, distribution_points):
          
  
          if distribution_points is None:
              return None
  
          for distribution_point in distribution_points:
              name = distribution_point['distribution_point']
              if name.name == 'full_name' and name.chosen[0].name == 'uniform_resource_identifier':
                  return name.chosen[0].chosen.native
  
          return None
docs: Grabs the first URL out of a asn1crypto.x509.CRLDistributionPoints
          object
  
          :param distribution_points:
              The x509.CRLDistributionPoints object to pull the URL out of
  
          :return:
              A unicode string or None