code: def inject(self, span_context, format, carrier):
          
          if format in Tracer._supported_formats:
              return
          raise UnsupportedFormatException(format)
docs: Injects `span_context` into `carrier`.
  
          The type of `carrier` is determined by `format`. See the
          :class:`Format` class/namespace for the built-in OpenTracing formats.
  
          Implementations *must* raise :exc:`UnsupportedFormatException` if
          `format` is unknown or disallowed.
  
          :param span_context: the :class:`SpanContext` instance to inject
          :type span_context: SpanContext
  
          :param format: a python object instance that represents a given
              carrier format. `format` may be of any type, and `format` equality
              is defined by python ``==`` equality.
          :type format: Format
          :param carrier: the format-specific carrier object to inject into