OptionalemphasizeHover fades the other series (default: true)
OptionaloverflowEntries beyond one row (top / bottom) or column (left / right): 'scroll' (default) pages
them behind ‹ › buttons; 'wrap' adds rows (top / bottom only; extra rows may cover the plot)
OptionalpositionSide of the plot (default 'top'); 'left' / 'right' stack the entries in a column sized to the longest name
OptionalshowDefault: true when there are 2+ series
OptionaltoggleClick toggles series visibility (default: true)
Legend shown above the plot (line / multi-series bar charts with 2+ series by default).