# Functions
NewCallWrapper accepts an opentracing Tracer and returns a Call Wrapper.
NewClientWrapper accepts an open tracing Trace and returns a Client Wrapper.
NewHandlerWrapper accepts an opentracing Tracer and returns a Handler Wrapper.
NewSubscriberWrapper accepts an opentracing Tracer and returns a Subscriber Wrapper.
StartSpanFromContext returns a new span with the given operation name and options.