Returns the unique alternative predicted by all alternative subsets in {@code altsets}. If no such alternative exists, this method returns {@link ATN#INVALID_ALT_NUMBER}.
@param altsets a collection of alternative subsets
See Implementation
Returns the unique alternative predicted by all alternative subsets in {@code altsets}. If no such alternative exists, this method returns {@link ATN#INVALID_ALT_NUMBER}.
@param altsets a collection of alternative subsets