Fix usage print
Fix usage print

rychipman/858-labs,rychipman/858-labs,emzhang/6858lab2,emzhang/6858lab2,darkmatter08/6858_labs_1_to_4,rychipman/858-labs,LeoTsui/6.858_lab,emzhang/6858lab2,LeoTsui/6.858_lab,emzhang/6858lab2,darkmatter08/6858_labs_1_to_4,LeoTsui/6.858_lab,emzhang/6858lab2,darkmatter08/6858_labs_1_to_4,darkmatter08/6858_labs_1_to_4,rychipman/858-labs,LeoTsui/6.858_lab,rychipman/858-labs,LeoTsui/6.858_lab,darkmatter08/6858_labs_1_to_4