public static SignedNumeral Format(this SignedNumeral signed) => ChurchSignedNumeral.Format(signed);
public static Numeral Positive(this SignedNumeral signed) => ChurchSignedNumeral.Positive(signed);
public static Numeral Negative(this SignedNumeral signed) => ChurchSignedNumeral.Negative(signed);
public static SignedNumeral Sign(this Numeral n) => ChurchSignedNumeral.Sign(n);