def mutate(self, info_in):
<EOL>if self.failed:<EOL><INDENT>raise ValueError("<STR_LIT>".format(self))<EOL><DEDENT>from .transformations import Mutation<EOL>info_out = type(info_in)(origin=self, contents=info_in._mutated_contents())<EOL>Mutation(info_in=info_in, info_out=info_out)<EOL>
Replicate an info + mutation.

        To mutate an info, that info must have a method called
        ``_mutated_contents``.