The code below defines a class called LB$\_$phone$\_$number, for representing a phone number in the $562($Long Beach$)$ area code. Several methods are missing code to finish their logic.

Complete the code above by filling in the bodies of the update$\_$number and print$\_$phone$\_$num methods:

update$\_$number : change the phone number $($not the area code$)$ to match the parameter to the method.

print$\_$phone$\_$num : print the phone number $-$ formatted as $"$XXX$-$YYY$-$YYYY$",$ where XXX is the area code, and YYY$-$YYYY is the phone number itself.