code: func mapAlloc(opts mapOptions) *Map {
  	m := &Map{mapOptions: opts}
  	m.Reallocate()
  	return m
  }
docs: // mapAlloc is a non-exported function so that when generating the source code
  // for the map you can supply a public constructor that sets the correct
  // hash, equals, copy, finalize options without users of the map needing to
  // implement them themselves.