a method to acquire an oauth access token

def access_token(self):

        ''' a method to acquire an oauth access token '''

        title = '%s.access_token' % self.__class__.__name__
    
    # import dependencies
        from time import time
        import requests

    # construct request kwargs
        request_kwargs = {
            'url': self.token_endpoint,
            'data': {
                'client_id': self.client_id,
                'client_secret': self.client_secret,
                'grant_type': 'client_credentials'
            }
        }

    # send request
        try:
            current_time = time()
            response = requests.post(**request_kwargs)
        except Exception:
            if self.requests_handler:
                request_kwargs['method'] = 'POST'
                request_object = requests.Request(**request_kwargs)
                return self.requests_handler(request_object)
            else:
                raise

        response_details = self.response_handler.handle(response)

        if response_details['json']:
            self._access_token = response_details['json']['access_token']
            expires_in = response_details['json']['expires_in']
            self.expires_at = current_time + expires_in
            
        return self._access_token