Write a function that, given a year and month, prints to the console the month calendar. The expected output format is as follows (the example is for December 2017):
Mon Tue Wed Thu Fri Sat Sun 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31