def extend(self, source, new_image_name, s2i_args=None):
raise NotImplementedError("<STR_LIT>")<EOL>
extend this s2i-enabled image using provided source, raises ConuException if
`s2i build` fails

:param source: str, source used to extend the image, can be path or url
:param new_image_name: str, name of the new, extended image
:param s2i_args: list of str, additional options and arguments provided to `s2i build`
:return: S2Image instance