Monkey patching Nulltracer from thrift. All our tracers have a start_span method, adding it to the NullTracer also.
Yields:
6 7 8 9
# File 'lib/zipkin-tracer/zipkin_null_tracer.rb', line 6 def with_new_span(trace_id, name) span = Span.new(name, trace_id) yield span end