new_contents: from client import APIBaseClient, verify_file
  
  
  class ContractingClient(APIBaseClient):
      """ contracting client """
  
      def __init__(self, key,
                   host_url="https://api-sandbox.openprocurement.org",
                   api_version='2.0',
                   params=None):
          super(ContractingClient, self).__init__(key, host_url, api_version,
                                                  "contracts", params)
  
      @verify_file
      def upload_document(self, file_, contract):
          return self._upload_resource_file(
              '{}/{}/documents'.format(
                  self.prefix_path,
                  contract.data.id
              ),
              data={"file": file_},
              headers={'X-Access-Token':
                       getattr(getattr(contract, 'access', ''), 'token', '')}
          )
  
      def create_contract(self, contract):
          return self._create_resource_item(self.prefix_path, contract)
  
      def get_contract(self, id):
          return self._get_resource_item('{}/{}'.format(self.prefix_path, id))
  
subject: add contracting client