def is_valid_op(self, op: Operation) -> bool:
        """Determines if op is valid for fp16 casting."""
        if op.op_type in self._UNSUPPORTED_FP16_OPS:
            return False

        if self.fp16_overflow(op):
            return False

        return True
Determines if op is valid for fp16 casting.
coremltools/converters/mil/mil/passes/defs/quantization.py