def backend_version(backend, childprocess=None):
if childprocess is None:<EOL><INDENT>childprocess = childprocess_default_value()<EOL><DEDENT>if not childprocess:<EOL><INDENT>return _backend_version(backend)<EOL><DEDENT>else:<EOL><INDENT>return run_in_childprocess(_backend_version, None, backend)<EOL><DEDENT>
Back-end version.

    :param backend: back-end (examples:scrot, wx,..)
    :param childprocess: see :py:func:`grab`
    :return: version as string