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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 build_info(self):
 """Get the build info of this Android device, including build id and build type. This is not available if the device is in bootloader mode. Returns: A dict with the build info of this Android device, or None if the device is in bootloader mode. """

        if self.is_bootloader:
            self.log.error('Device is in fastboot mode, could not get build '
                           'info.')
            return
        info = {}
        info['build_id'] = self.adb.getprop('ro.build.id')
        info['build_type'] = self.adb.getprop('ro.build.type')
        return info