https://github.com/influxdb/influxdb-python/blob/df7fa9646b56a775c0494aadb3ea1ae41deb1ed8/influxdb/client.py#L143

This code could be replaced by just using request's json=... keyword argument, which is converted to a JSON string inside requests. This would require that all occurences of data=...somedict... in the code be replaced by json=...somedict....

There actually doesn't seem to be any case of data being a string in the code base. This means that all the logic testing for str could be stripped from the client and the tests.