anchor.diff:    /// This precludes a NaN value like [double.nan] from being negative.
     bool get isNegative;
   
  -  /// Whether the number is positive infinity or negative infinity.
  +  /// Whether this number is positive infinity or negative infinity.
     ///
     /// Only satisfied by [double.infinity] and [double.negativeInfinity].
     ///
  
positive.code:   /// and [isNaN].
    bool get isInfinite;
  
    /// Whether the number is finite.
    ///
    /// The only non-finite numbers are NaN values, positive infinity, and
    /// negative infinity. All integers are finite.
  
negative.code:   /// plus one if this number is greater than zero,
    /// and zero if this number is equal to zero.
    ///
    /// Returns NaN if this number is a [double] NaN value.
    ///
    /// Returns a number of the same type as this number.
    /// For doubles, `(-0.0).sign` is `-0.0`.
  