argument.

:param list,str path: one or more relays to make a circuit through
:param str purpose: 'general' or 'controller'
:param bool await_build: blocks until the circuit is built if **True**
:param float timeout: seconds to wait when **await_build** is **True**

:returns: str of the circuit id of the newly created circuit

:raises:
  * :class:`stem.ControllerError` if the call fails
  * :class:`stem.Timeout` if **timeout** was reached
r¿