def usage(self):
c = self._s2i_command(["<STR_LIT>", self.get_full_name()])<EOL>with open(os.devnull, "<STR_LIT:w>") as fd:<EOL><INDENT>process = subprocess.Popen(c, stdout=fd, stderr=subprocess.PIPE)<EOL>_, output = process.communicate()<EOL>retcode = process.poll()<EOL><DEDENT>if retcode:<EOL><INDENT>raise ConuException("<STR_LIT>" % output)<EOL><DEDENT>return output.decode("<STR_LIT:utf-8>").strip()<EOL>
Provide output of `s2i usage`

:return: str