public string ToString_WithOthersFormatString(string format)
        {
            Customer customer = new Customer("Jeffrey Richter", "+1 (425) 555-0100", 1000000);
            Stopwatch watch = new Stopwatch();

            string actResultString = customer.ToString(format);
            
            return actResultString;
        }
 private string FormatCustomerWithDoubleQuote(Customer customer)
 {
     return String.Format("Name: \"{0}\" ContactPhone: \"{1}\" Revenue: \"{2}\"",
         customer.Name, customer.ContactPhone, customer.Revenue);
 }
 private string FormatCustomerWithSingleQuote(Customer customer)
 {
     return String.Format("Name: '{0}' ContactPhone: '{1}' Revenue: '{2}'",
         customer.Name, customer.ContactPhone, customer.Revenue);
 }
 private string FormatCustomerWithNewLine(Customer customer)
 {
     return String.Format("Name: {0}\n ContactPhone: {1}\n Revenue: {2}\n",
         customer.Name, customer.ContactPhone, customer.Revenue);
 }
 private string FormatCustomerWithTab(Customer customer)
 {
     return String.Format("Name: {0}\t ContactPhone: {1}\t Revenue: {2}\t",
         customer.Name, customer.ContactPhone, customer.Revenue);
 }