Create a streaming session for use with the Tradier Streaming API. This session can be used with the streaming endpoints to obtain updates to the market 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.