code: public Tuple set(Enum<?> eval, Object val) {
          set(eval.ordinal(), val);
          return this;
      }
docs: Sets a value at a specific position in the tuple.
  <p/>
  The position is determined by executing {@link Enum#ordinal()} on the supplied enum.
  <p/>
  If this tuple has fewer elements than the index being set, then the tuple will grow to
  {@code idx} elements.
  
  @param eval the enum which is used to determine the index for the set operation
  @param val  the value to set
  @return a handle to this object to enable builder operations