Currently start_span() in different languages has different activation semantics: in Java and Ruby, it does not set the newly created Span as the active instance, while Python does (Go seems to offer to do it if you pass a Context).

In OpenTracing, for this purpose, we had start_span() and start_active_span().

Hence I'd suggest renaming the related methods:

• create_span() -> start_span()
• start_span() -> start_current_span() or similar

This will most likely impact the Specification itself at some degree, but wanted to ask here first about your opinion ;)