pie.set_series_opts(label_opts=opts.LabelOpts(formatter="{b}:{d}%"))

Null is a term used to indicate the absence of a value or an empty state. In computing, null is often used to represent a missing or undefined value, such as the absence of a variable or the lack of data in a database field. Null can also refer to a zero value or a placeholder value used to indicate that a value has not yet been assigned. In programming languages, null is often represented as a keyword or a special value that can be checked for and handled by the program.