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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 _bin(self, bin):
 # type: (str) -> str """ Return path to the given executable. """

        bin_path = (self._bin_dir / bin).with_suffix(".exe" if self._is_windows else "")
        if not bin_path.exists():
            return bin

        return str(bin_path)