def METHOD_NAME(self, var):
    """Return barebox environment variable value via 'fastboot oem getenv <var>'."""
    cmd = ['oem', 'getenv', var]
    output = processwrapper.check_output(self._get_fastboot_prefix() + cmd)
    values = AndroidFastbootDriver._filter_fastboot_output(output)
    assert len(values) == 1, 'fastboot did not return exactly one line'
    return values[0]