code: def find_usage(self):
          
          ignore_statuses = [
              'DELETE_COMPLETE'
          ]
          logger.debug("Checking usage for service %s", self.service_name)
          self.connect()
          for lim in self.limits.values():
              lim._reset_usage()
          count = 0
          paginator = self.conn.get_paginator('describe_stacks')
          iter = paginator.paginate()
          for page in iter:
              for stk in page['Stacks']:
                  if stk['StackStatus'] not in ignore_statuses:
                      count += 1
          self.limits['Stacks']._add_current_usage(
              count, aws_type='AWS::CloudFormation::Stack'
          )
          self._have_usage = True
          logger.debug("Done checking usage.")
docs: Determine the current usage for each limit of this service,
          and update corresponding Limit via
          :py:meth:`~.AwsLimit._add_current_usage`.