Following are the one-liner and execution samples:
>>> import random
>>> import string
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'DbtmlV'
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'SUXluh'
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'YpeAu9'
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'fFdFgF'
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'okhQcY'
>>> ''.join(map(lambda x: random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits), range(6)))
'1HPOID'