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!'.
More in this series:
The Office I - Outed
The Office II - Boredeom Score
The Office III - Broken Photocopier
The Office V - Find a Chair
def meeting(rooms):
    return next((i for i, r in enumerate(rooms) if r == 'O'), 'None available!')
def meeting(rooms):
    return next((i for i, r in enumerate(rooms) if r == 'O'), 'None available!')