def apply_mutation(wfid, pdef)

      Mutation.new(self, wfid, @context.reader.read(pdef)).apply
    end
def apply_mutation(wfid, pdef)

      Mutation.new(self, wfid, @context.reader.read(pdef)).apply
    end
Computes mutation and immediately applies it...

 See #compute_mutation

 Return the mutation instance (forensic?)