How to use the instana.singletons.tracer.extract function in instana

def new_start_response(status, headers, exc_info=None):
            """Modified start response with additional headers."""
            tracer.inject(self.scope.span.context, ot.Format.HTTP_HEADERS, headers)
            headers.append(('Server-Timing', "intid;desc=%s" % self.scope.span.context.trace_id))

            res = start_response(status, headers, exc_info)

            sc = status.split(' ')[0]
            if 500 <= int(sc) <= 511:
                self.scope.span.mark_as_errored()

            self.scope.span.set_tag(tags.HTTP_STATUS_CODE, sc)
            self.scope.close()
            return res

        ctx = tracer.extract(ot.Format.HTTP_HEADERS, env)
        self.scope = tracer.start_active_span("wsgi", child_of=ctx)

        if hasattr(agent, 'extra_headers') and agent.extra_headers is not None:
            for custom_header in agent.extra_headers:
                # Headers are available in this format: HTTP_X_CAPTURE_THIS
                wsgi_header = ('HTTP_' + custom_header.upper()).replace('-', '_')
                if wsgi_header in env:
                    self.scope.span.set_tag("http.%s" % custom_header, env[wsgi_header])

        if 'PATH_INFO' in env:
            self.scope.span.set_tag('http.path', env['PATH_INFO'])
        if 'QUERY_STRING' in env and len(env['QUERY_STRING']):
            scrubbed_params = strip_secrets(env['QUERY_STRING'], agent.secrets_matcher, agent.secrets_list)
            self.scope.span.set_tag("http.params", scrubbed_params)
        if 'REQUEST_METHOD' in env:
            self.scope.span.set_tag(tags.HTTP_METHOD, env['REQUEST_METHOD'])

tracer.inject(scope.span.context, ot.Format.HTTP_HEADERS, headers)
                headers.append(('Server-Timing', "intid;desc=%s" % scope.span.context.trace_id))

                res = start_response(status, headers, exc_info)

                sc = status.split(' ')[0]
                if 500 <= int(sc) <= 511:
                    scope.span.mark_as_errored()

                scope.span.set_tag(tags.HTTP_STATUS_CODE, sc)
                scope.close()
                return res
            else:
                return start_response(status, headers, exc_info)

        ctx = tracer.extract(ot.Format.HTTP_HEADERS, env)
        scope = env['stan_scope'] = tracer.start_active_span("wsgi", child_of=ctx)

        if hasattr(agent, 'extra_headers') and agent.extra_headers is not None:
            for custom_header in agent.extra_headers:
                # Headers are available in this format: HTTP_X_CAPTURE_THIS
                wsgi_header = ('HTTP_' + custom_header.upper()).replace('-', '_')
                if wsgi_header in env:
                    scope.span.set_tag("http.%s" % custom_header, env[wsgi_header])

        if 'PATH_INFO' in env:
            scope.span.set_tag('http.path', env['PATH_INFO'])
        if 'QUERY_STRING' in env and len(env['QUERY_STRING']):
            scrubbed_params = strip_secrets(env['QUERY_STRING'], agent.secrets_matcher, agent.secrets_list)
            scope.span.set_tag("http.params", scrubbed_params)
        if 'REQUEST_METHOD' in env:
            scope.span.set_tag(tags.HTTP_METHOD, env['REQUEST_METHOD'])

def before_request_with_instana(*argv, **kwargs):
    try:
        env = flask.request.environ
        ctx = None

        if 'HTTP_X_INSTANA_T' in env and 'HTTP_X_INSTANA_S' in env:
            ctx = tracer.extract(opentracing.Format.HTTP_HEADERS, env)

        flask.g.scope = tracer.start_active_span('wsgi', child_of=ctx)
        span = flask.g.scope.span

        if hasattr(agent, 'extra_headers') and agent.extra_headers is not None:
            for custom_header in agent.extra_headers:
                # Headers are available in this format: HTTP_X_CAPTURE_THIS
                header = ('HTTP_' + custom_header.upper()).replace('-', '_')
                if header in env:
                    span.set_tag("http.%s" % custom_header, env[header])

        span.set_tag(ext.HTTP_METHOD, flask.request.method)
        if 'PATH_INFO' in env:
            span.set_tag(ext.HTTP_URL, env['PATH_INFO'])
        if 'QUERY_STRING' in env and len(env['QUERY_STRING']):
            scrubbed_params = strip_secrets(env['QUERY_STRING'], agent.secrets_matcher, agent.secrets_list)

def process_request(self, request):
        try:
            env = request.environ

            ctx = tracer.extract(ot.Format.HTTP_HEADERS, env)
            request.iscope = tracer.start_active_span('django', child_of=ctx)

            if hasattr(agent, 'extra_headers') and agent.extra_headers is not None:
                for custom_header in agent.extra_headers:
                    # Headers are available in this format: HTTP_X_CAPTURE_THIS
                    django_header = ('HTTP_' + custom_header.upper()).replace('-', '_')
                    if django_header in env:
                        request.iscope.span.set_tag("http.%s" % custom_header, env[django_header])

            request.iscope.span.set_tag(ext.HTTP_METHOD, request.method)
            if 'PATH_INFO' in env:
                request.iscope.span.set_tag(ext.HTTP_URL, env['PATH_INFO'])
            if 'QUERY_STRING' in env and len(env['QUERY_STRING']):
                scrubbed_params = strip_secrets(env['QUERY_STRING'], agent.secrets_matcher, agent.secrets_list)
                request.iscope.span.set_tag("http.params", scrubbed_params)
            if 'HTTP_HOST' in env:

def call_behavior_with_instana(wrapped, instance, argv, kwargs):
        # Prep any incoming context headers
        metadata = argv[0].invocation_metadata
        metadata_dict = {}
        for c in metadata:
            metadata_dict[c.key] = c.value

        ctx = tracer.extract(opentracing.Format.BINARY, metadata_dict)

        with tracer.start_active_span("rpc-server", child_of=ctx) as scope:
            try:
                collect_tags(scope.span, instance, argv, kwargs)
                rv = wrapped(*argv, **kwargs)
            except Exception as e:
                scope.span.log_exception(e)
                raise
            else:
                return rv

def request_started_with_instana(sender, **extra):
    try:
        env = flask.request.environ
        ctx = None

        if 'HTTP_X_INSTANA_T' in env and 'HTTP_X_INSTANA_S' in env:
            ctx = tracer.extract(opentracing.Format.HTTP_HEADERS, env)

        flask.g.scope = tracer.start_active_span('wsgi', child_of=ctx)
        span = flask.g.scope.span

        if hasattr(agent, 'extra_headers') and agent.extra_headers is not None:
            for custom_header in agent.extra_headers:
                # Headers are available in this format: HTTP_X_CAPTURE_THIS
                header = ('HTTP_' + custom_header.upper()).replace('-', '_')
                if header in env:
                    span.set_tag("http.%s" % custom_header, env[header])

        span.set_tag(ext.HTTP_METHOD, flask.request.method)
        if 'PATH_INFO' in env:
            span.set_tag(ext.HTTP_URL, env['PATH_INFO'])
        if 'QUERY_STRING' in env and len(env['QUERY_STRING']):
            scrubbed_params = strip_secrets(env['QUERY_STRING'], agent.secrets_matcher, agent.secrets_list)