Nikki has a new phone number (304-5083) and wants to create a clever way for everyone to remember it. On older telephones, the keypad associates letters with each numeral. Given a seven-digit telephone number, return an array of all possible strings that equate to that phone number. For reference, here is the mapping: [2:ABC; 3:DEF; 4:GHI; 5:JKL; 6:MNO; 7:PQRS; 8:TUV; 9:WXYZ] – for completeness, map 1 to I and zero to O. For example, given a phone number 818-2612, return an array of 243 different strings, including “vitamic” and “titania”.