style-to-index in style-list%

Returns the index for a particular style. The index for a style's base style (and shift style, if it is a join style) is guaranteed to be lower than the style's own index. (As a result, the root style's index is always 0.) A style's index can change whenever a new style is added to the list, or the base style or shift style of another style is changed.

If the given style is not in this list, #f is returned.

• (send a-style-list style-to-index style) -> exact non-negative integer or #f
   style : style<%> object