nearest_frame_to_timepoint
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.. py:function:: petpal.utils.useful_functions.nearest_frame_to_timepoint(frame_times: numpy.ndarray) -> collections.abc.Callable[[float], float]

   Returns a step function that gets the index of the frame closest to a provided timepoint
   based on an array of frame times, such as the frame starts or reference times.

   :param frame_times: The frame times on which to generate the step function.
   :type frame_times: np.ndarray

   :returns: *nearest_frame_func (Callable[[float],float])* --

             A function that returns the time closest to
                 the provided timepoint.