func NewColumnIterator(format Format, reader io.Reader) *Iterator {
	return NewIterator(reader, ColumnUnmarshaller(format))
}
func NewColumnIterator(format Format, reader io.Reader) *Iterator {
	return NewIterator(reader, ColumnUnmarshaller(format))
}
func NewColumnIterator ( format Format , reader io . Reader ) * Iterator { return NewIterator ( reader , ColumnUnmarshaller ( format ) ) }
// NewColumnIterator creates a new iterator for column data.
NewColumnIterator creates a new iterator for column data .