code: public static final <T> Function<T,Boolean> not(final IFunction<T, Boolean> function) {
          return new Not<T>(function);
      }
docs: <p>
  Takes a boolean function (<tt>Function&lt;?,Boolean&gt;</tt>) as a
  parameter and returns another one which returns true if the specified function
  returns false, and false if the function returns true.
  </p>
  
  @param function the function to be negated
  @return a function returning true if the specified function returns false, and false if
  it returns true.