/// <summary>
        /// If the formula parameter is null, throws an ArgumentNullException.
        /// 
        /// Otherwise, if name is null or invalid, throws an InvalidNameException.
        /// 
        /// Otherwise, if changing the contents of the named cell to be the formula would cause a 
        /// circular dependency, throws a CircularException.  (No change is made to the spreadsheet.)
        /// 
        /// Otherwise, the contents of the named cell becomes formula.  The method returns a
        /// Set consisting of name plus the names of all other cells whose value depends,
        /// directly or indirectly, on the named cell.
        /// 
        /// For example, if name is A1, B1 contains A1*2, and C1 contains B1+A1, the
        /// set {A1, B1, C1} is returned.
        /// </summary>
        public ISet<String> SetCellContents(String name, Formula formula)
        {
            if (formula.equals(null))
            {
                throw ArgumentNullException;

            }
            else if (name.Equals(null))
            {
                throw InvalidNameException;

            }
            else
            {

            }
        }