code: def get_all_reserved_instances_offerings(self, reserved_instances_id=None,
                                               instance_type=None,
                                               availability_zone=None,
                                               product_description=None,
                                               filters=None):
          
          params = {}
          if reserved_instances_id:
              params['ReservedInstancesId'] = reserved_instances_id
          if instance_type:
              params['InstanceType'] = instance_type
          if availability_zone:
              params['AvailabilityZone'] = availability_zone
          if product_description:
              params['ProductDescription'] = product_description
          if filters:
              self.build_filter_params(params, filters)
  
          return self.get_list('DescribeReservedInstancesOfferings',
                               params, [('item', ReservedInstancesOffering)],
                               verb='POST')
docs: Describes Reserved Instance offerings that are available for purchase.
  
          :type reserved_instances_id: str
          :param reserved_instances_id: Displays Reserved Instances with the
                                        specified offering IDs.
  
          :type instance_type: str
          :param instance_type: Displays Reserved Instances of the specified
                                instance type.
  
          :type availability_zone: str
          :param availability_zone: Displays Reserved Instances within the
                                    specified Availability Zone.
  
          :type product_description: str
          :param product_description: Displays Reserved Instances with the
                                      specified product description.
  
          :type filters: dict
          :param filters: Optional filters that can be used to limit
                          the results returned.  Filters are provided
                          in the form of a dictionary consisting of
                          filter names as the key and filter values
                          as the value.  The set of allowable filter
                          names/values is dependent on the request
                          being performed.  Check the EC2 API guide
                          for details.
  
          :rtype: list
          :return: A list of :class:`boto.ec2.reservedinstance.ReservedInstancesOffering`