public static S fold <L, R, S>(Either <L, R> either, S state, Func <S, R, S> Right, Func <S, L, S> Left) => either.Fold(state, Right, Left);
public static S fold <S, R, L>(Either <R, L> either, S state, Func <S, R, S> folder) => either.Fold(state, folder);
public static S fold <S, L, R>(Either <L, R> either, S state, Func <S, L, S> folder) => either.Fold(state, folder);