def main(argv):
if not argv:
print('No input file supplied!')
return
cwd = os.getcwd()
input_f = os.path.join(cwd, argv[0])
if len(argv) > 1:
output_f = os.path.join(cwd, argv[1])
sys.stdout = open(output_f, 'w')
try:
world = World(input_f)
world.start()
except IOError:
print('Input file does not exist!')
except SimulationException as e:
print(e)
