Tracing flask incoming requests, outbound requests, internal functions calls, especially gevent parallel http calls or functions calls
python setup.py install --userhttps://github.com/darinautilus/opentracing-flask-example
https://github.com/opentracing/opentracing-python/blob/master/opentracing/scope_managers/gevent.py#L41 https://github.com/opentracing/opentracing-python#outbound-request