#From version 3.4, the Python language can natively manage this case.
#The makedirs() function accepts a second parameter, exist_ok.
#By setting the value to true, the method will not throw an exception
# if the directory already exists
os.makedirs(repertoire, exist_ok=True)
#other method
if not os.path.exists(repertoire):
os.makedirs(repertoire)
#other method
try:
os.makedirs(repertoire)
except OSError:
if not os.path.isdir(repertoire):
Raise