val skip : decoder -> [ A | O | Element | Member ] -> unit
(** [skip d construct] skips lexemes depending on [construct]:
{ul
{- [A] skips {e past} the [A_end] matching the last decoded [A_start].} {- [O] skips {e past} the [O_end] matching the last decoded [O_start].}
{- [Element] skips {e to} the next element of the last decoded [A_start] or {e to} [A_end] if there is none.} {- [Member] skips {e to} the next [Name] of the last decoded [O_start] or {e to} [`O_end] if there is none.}}
{b Raises} [Invalid_argument] if [d] is not in the right
state to skip [construct]. *)