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Tuple2.java

import org.jetbrains.annotations.NotNull;

import java.util.function.Function;

public interface Tuple2<T1, T2> {
    @NotNull
    T1 t1();

    @NotNull
    T2 t2();

    @NotNull
    default T1 left() {
        return t1();
    }

    @NotNull
    default T2 right() {
        return t2();
    }

    <R1> Tuple2<R1, T2> mapT1(@NotNull Function<? super T1, ? extends R1> mapper);

    <R2> Tuple2<T1, R2> mapT2(@NotNull Function<? super T2, ? extends R2> mapper);

    static <T1, T2> Tuple2<T1, T2> of(T1 t1, T2 t2) {
        return new ValueTuple2<>(t1, t2);
    }
}