@classmethod
    def call(cls, typemap, args, kws):
        """Perform the entire ufunc call mechanism.
        """
        # Handle keywords
        stream = kws.pop('stream', cls.DEFAULT_STREAM)
        out = kws.pop('out', None)

        if kws:
            warnings.warn("unrecognized keywords: %s" % ', '.join(kws))

        # Begin call resolution
        cr = cls(typemap, args)
        args = cr.get_arguments()
        resty, func = cr.get_function()

        outshape = args[0].shape

        def attempt_ravel(a):
            if cr.SUPPORT_DEVICE_SLICING:
                raise NotImplementedError

            try:
                # Call the `.ravel()` method
                return a.ravel()
            except NotImplementedError:
                # If it is not a device array
                if not cr.is_device_array(a):
                    raise
                # For device array, retry ravel on the host by first
                # copying it back.
                else:
                    hostary = cr.to_host(a, stream).ravel()
                    return cr.to_device(hostary, stream)

        if args[0].ndim > 1:
            args = [attempt_ravel(a) for a in args]

        # Prepare argument on the device
        devarys = []
        any_device = False
        for a in args:
            if cr.is_device_array(a):
                devarys.append(a)
                any_device = True
            else:
                dev_a = cr.to_device(a, stream=stream)
                devarys.append(dev_a)

        # Launch
        shape = args[0].shape
        if out is None:
            # No output is provided
            devout = cr.device_array(shape, resty, stream=stream)

            devarys.extend([devout])
            cr.launch(func, shape[0], stream, devarys)

            if any_device:
                # If any of the arguments are on device,
                # Keep output on the device
                return devout.reshape(outshape)
            else:
                # Otherwise, transfer output back to host
                return devout.copy_to_host().reshape(outshape)

        elif cr.is_device_array(out):
            # If output is provided and it is a device array,
            # Return device array
            if out.ndim > 1:
                out = attempt_ravel(out)
            devout = out
            devarys.extend([devout])
            cr.launch(func, shape[0], stream, devarys)
            return devout.reshape(outshape)

        else:
            # If output is provided and it is a host array,
            # Return host array
            assert out.shape is not shape
            assert out.dtype == resty
            devout = cr.device_array(shape, resty, stream=stream)
            devarys.extend([devout])
            cr.launch(func, shape[0], stream, devarys)
            return devout.copy_to_host(out, stream=stream).reshape(outshape)
dataset/ETHPy150Open numba/numba/numba/npyufunc/deviceufunc.py/UFuncMechanism.call/operator `==` -> `is not`