code: public static DoubleBinding exp(final ObservableDoubleValue a) {
          return createDoubleBinding(() -> Math.exp(a.get()), a);
      }
docs: Binding for {@link java.lang.Math#exp(double)}
  
  @param   a   the exponent to raise <i>e</i> to.
  @return  the value <i>e</i><sup>{@code a}</sup>,
  where <i>e</i> is the base of the natural logarithms.