def start_span(self, name='span'):
"""Start a span.
:type name: str
:param name: The name of the span.
:rtype: :class:`~opencensus.trace.trace_span.Span`
:returns: The Span object.
"""
return trace_span.BlankSpan(name, context_tracer=self)
def current_span(self):
"""Return the current span."""
return trace_span.BlankSpan()