You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sink.rb
    path of file: ./repos/mutant/lib/mutant/mutation/runner
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Mutant
  class Mutation
    module Runner
      class Sink
        include Parallel::Sink

        include Anima.ne
    
        def mutation_result(mutation_index_result)
          Result::Mutation.new(
            isolation_result: mutation_index_result.isolation_result,
            mutation:         env.mutations.fetch(mutation_index_result.mutation_index),
            runtime:          mutation_index_result.runtime
          )
        end