code: public static DoubleBinding copySign(final ObservableDoubleValue magnitude, double sign) {
          return createDoubleBinding(() -> Math.copySign(magnitude.get(), sign), magnitude);
      }
docs: Binding for {@link java.lang.Math#copySign(double, double)}
  
  @param magnitude  the parameter providing the magnitude of the result
  @param sign   the parameter providing the sign of the result
  @return a value with the magnitude of {@code magnitude}
  and the sign of {@code sign}.