Create a streaming session for use with the Tradier Streaming API. This session can be used with the streaming endpoints to obtain account updates such as order status changes as they happen.
Note: Once a sessionid is received, it will be valid for 5 minutes, during which time you can initiate a stream. After the session expires and you’ll need to create a new session in order to stream data.
Content-length: 0header in cases where the POST request doesn't include a body.