code: func NewStreamVisitor(r io.Reader, mapper *mapper, source string, schema ContentValidator) *StreamVisitor {
  	return &StreamVisitor{
  		Reader: r,
  		mapper: mapper,
  		Source: source,
  		Schema: schema,
  	}
  }
docs: // NewStreamVisitor is a helper function that is useful when we want to change the fields of the struct but keep calls the same.