6.1. Send Bulk SMS

A small business wants to send bulk messages to a group of customers to boost their sales and to annoy the people (mostly to annoy the people). The phone book of the customers they have is implemented as a dictionary in the following buggy function which takes the name of person as a string and return their phone number in the same type:

def get_phone_number(person):
    phone_dict = {"Jerry Seinfeld":"+1 960-454-6956",
                  "George Constanza":"+1 844-833-4965",
                  "Elaine Benes":"+1 543-920-5729",
                  "Cosmo Kramer":"+1 556-673-6702",
                  "Jim Halpert":"+1 867-767-7664",
                  "Pam Beesly":"+1 410-570-7381",
                  "Michael Scott":"+1 657-220-6601",
                  "Dwight Schrute":"+1 940-573-6702",
                  "Rachel Green":"+1 813-856-3347",
                  "Monica Geller":"+1 527-324-1403",
                  "Ross Geller":"+1 687-801-6781",
                  "Phoebe Buffay":"+1 208-702-5161",
                  "Joey Tribbiani":"+1 908-665-3975",
                  "Chandler Bing":"+1 444-970-5300"}

    return phone_dict[person]

Why we called this function buggy? Because it never checks whether the given person is in the phone book or not. In Python, if a dictionary does not have the given key, \(\color{purple}{\texttt{KeyError}}\) exception is raised.

Although the function above is not safe for direct use, we have the reliable function that takes a phone number as a string, sends SMS to that phone number (hypothetically) and returns True, indicating that the process is successfully performed, as given below:

def send_sms(number):
    # sends message #
    print("Message is successfully sent to " + number)
    return True

Write a function named ``send_bulk_sms`` which takes a list of customers’ names as a list of strings and sends message to each of them whose number is registered in the phone book by using the functions above. Obviously, any exception thrown by ``get_phone_number`` function must be handled in your implementation and reported in the following format:

“Customer is not found in the phone book: {Customer Name}”

Note: We normally do not want a function to print anything beside doing its task and return the value as it is excepted. However, in this case, the function is required to do logging. Therefore, it is proper to use \(\color{purple}{\texttt{print()}}\) function and not to return any value.

Sample I/O:

>>> send_bulk_sms(["Michael Scott", "Dwight Schrute", "Joey Tribbiani"])
Message is successfully sent to +1 657-220-6601
Message is successfully sent to +1 940-573-6702
Message is successfully sent to +1 908-665-3975

>>> send_bulk_sms(["Pam Beesly", "George Constanza", "Elaine Benes", "Michael Scott", "Maurice Moss"])
Message is successfully sent to +1 410-570-7381
Message is successfully sent to +1 844-833-4965
Message is successfully sent to +1 543-920-5729
Message is successfully sent to +1 657-220-6601
Customer is not in the phone book: Maurice Moss

>>> send_bulk_sms(["Roy Trenneman", "Monica Geller", "Michael Scott", "Pam Beesly",
                   "Maurice Moss", "Jen Barber", "Ross Geller", "Joey Tribbiani",
                   "Phoebe Buffay", "Denholm Reynholm", "Jim Halpert", "Cosmo Kramer",
                   "Dwight Schrute", "Jerry Seinfeld", "George Constanza"])
Customer is not in the phone book: Roy Trenneman
Message is successfully sent to +1 527-324-1403
Message is successfully sent to +1 657-220-6601
Message is successfully sent to +1 410-570-7381
Customer is not in the phone book: Maurice Moss
Customer is not in the phone book: Jen Barber
Message is successfully sent to +1 687-801-6781
Message is successfully sent to +1 908-665-3975
Message is successfully sent to +1 208-702-5161
Customer is not in the phone book: Denholm Reynholm
Message is successfully sent to +1 867-767-7664
Message is successfully sent to +1 556-673-6702
Message is successfully sent to +1 940-573-6702
Message is successfully sent to +1 960-454-6956
Message is successfully sent to +1 844-833-4965

Show the Answer

def send_bulk_sms(list_of_customers):
    for customer in list_of_customers:
        try:
            number = get_phone_number(customer)
            send_sms(number)
        except KeyError:
            print("Customer is not found in the phone book: " + customer)