code: func AddConversion(in interface{}, out interface{}, converter Converter) {
  	srcType := extractType(in)
  	targetType := extractType(out)
  	AddConversionByType(srcType, targetType, converter)
  }
docs: // AddConversion mothod allows registering a custom `Converter` into the global `converterMap`
  // by supplying pointers of the target types.