<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def start_capture(self, data_link_type="DLT_EN10MB", capture_file_name=None):
 """ Start capture on the link :returns: Capture object """


        self._capturing = True
        self._capture_file_name = capture_file_name
        self._streaming_pcap = asyncio.async(self._start_streaming_pcap())
        self._project.controller.notification.emit("link.updated", self.__json__())