Your job at E-Corp is both boring and difficult. It isn't made any easier by the fact that everyone constantly wants to have a meeting with you, and that the meeting rooms are always taken!
In this kata, you will be given an array. Each value represents a meeting room. Your job? Find the first empty one and return its index (N.B. There may be more than one empty room in some test cases).
'X' --> busy 'O' --> empty
If all rooms are busy, return 'None available!'.