def knock_out(self):
self.functional = False<EOL>for reaction in self.reactions:<EOL><INDENT>if not reaction.functional:<EOL><INDENT>reaction.bounds = (<NUM_LIT:0>, <NUM_LIT:0>)<EOL><DEDENT><DEDENT>
Knockout gene by marking it as non-functional and setting all
        associated reactions bounds to zero.

        The change is reverted upon exit if executed within the model as
        context.