code: def _get_headers(self):
          
  
          user_agent = __api_lib_name__ + '/' + __version__ + '/' + \
              PYTHON_VERSION
  
          headers = {'User-Agent': user_agent,
                     'Content-Type': 'application/x-www-form-urlencoded'}
          if self.key:
              headers['Authorization'] = 'Bearer ' + self.key
          return headers
docs: Get all the headers we're going to need:
  
          1. Authorization
          2. Content-Type
          3. User-agent
  
          Note that the User-agent string contains the library name, the
          libary version, and the python version. This will help us track
          what people are using, and where we should concentrate our
          development efforts.