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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 register_postcmd_hook(self, func: Callable[[plugin.PostcommandData], plugin.PostcommandData]) -> None: """Register a hook to be called after the command function."""

        self._validate_prepostcmd_hook(func, plugin.PostcommandData)
        self._postcmd_hooks.append(func)