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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def dumps(self, config, instance, prefer=None, **kwargs):
 """ An abstract dumps method which dumps an instance into the subclasses format. :param class config: The config class of the instance :param object instance: The instance to dump :param str prefer: The preferred serialization module name :raises ValueError: If dump handler does not provide handler method :return: The dumped content :rtype: str """


        dumper = self._prefer_package(prefer)
        dumps_hook_name = f"on_{dumper}_dumps"
        dumps_hook = getattr(self, dumps_hook_name, None)
        if not callable(dumps_hook):
            raise ValueError(
                f"no dumps handler for {self.imported!r}, requires method "
                f"{dumps_hook_name!r} in {self!r}"
            )

        extras = self.options.copy()
        for (key, value) in kwargs.items():
            if key not in extras.keys():
                warnings.warn(
                    f"handler 'dumps_{self.name!s}' does not support {key!r} argument"
                )
            else:
                extras[key] = value
        return dumps_hook(self.handler, config, instance, **extras)