How to use the opentelemetry-sdk.src.opentelemetry.sdk.trace.__init__.Tracer.CURRENT_SPAN function in opentelemetry-sdk

def start_span(  # pylint: disable=too-many-locals
        self,
        name: str,
        parent: trace_api.ParentSpan = trace_api.Tracer.CURRENT_SPAN,
        kind: trace_api.SpanKind = trace_api.SpanKind.INTERNAL,
        attributes: Optional[types.Attributes] = None,
        links: Sequence[trace_api.Link] = (),
        start_time: Optional[int] = None,
        set_status_on_exception: bool = True,
    ) -> trace_api.Span:
        """See `opentelemetry.trace.Tracer.start_span`."""

        if parent is Tracer.CURRENT_SPAN:
            parent = self.get_current_span()

        parent_context = parent
        if isinstance(parent_context, trace_api.Span):
            parent_context = parent.get_context()

        if parent_context is not None and not isinstance(
            parent_context, trace_api.SpanContext
        ):
            raise TypeError

        if parent_context is None or not parent_context.is_valid():
            parent = parent_context = None
            trace_id = generate_trace_id()
            trace_options = None
            trace_state = None