code: @Nonnull
    public CSSExpression addNumber (@Nonnegative final int nIndex, final float fValue)
    {
      return addMember (nIndex, new CSSExpressionMemberTermSimple (fValue));
    }
docs: Shortcut method to add a numeric value
  
  @param nIndex
  The index where the member should be added. Must be &ge; 0.
  @param fValue
  The value to be added.
  @return this