Not able to create transaction - iControl REST

Here is a sample of what I use with Python's requests module. I send an empty payload which seems to work.

uri = "https://IP/mgmt/tm/transaction"
response = bigip.post(uri, data=json.dumps({}))

This will return a JSON response with a transId value, which must be passed into every other request that should be part of the transaction. The transId value should be passed as the value to the header "X-F5-REST-Coordination-Id".

headers = {'X-F5-REST-Coordination-Id': transId}