A condition that monitors a state.
This condition is delayed.
This condition continuously monitors the state of a callback function. When
the callback's return value matches a provided target value, the condition
is satisfied. If this does not occur within an optional timeout (specified
in ms), @ref PrecedingTimeoutError is set. Set timeout to None for no
timeout. The callback will be called at the frequency specified, in Hertz.
The callback will be passed all the arguments that get passed to @ref
set_args. It should accept any arguments it needs, as well as *args and
**kwargs.
Definition at line 442 of file plan.py.