import os
p = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
def gen_token(n):
t = ""
while n > 0:
i = ord(os.urandom(1))
while i >= 248:
i = ord(os.urandom(1))
i %= 62
t += p[i]
n -= 1
return t
print gen_token(64)
aW1wb3J0IG9zCgpwID0gImFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVowMTIzNDU2Nzg5IgpkZWYgZ2VuX3Rva2VuKG4pOgogIHQgPSAiIgogIHdoaWxlIG4gPiAwOgogICAgaSA9IG9yZChvcy51cmFuZG9tKDEpKQogICAgd2hpbGUgaSA+PSAyNDg6CiAgICAgIGkgPSBvcmQob3MudXJhbmRvbSgxKSkKICAgIGkgJT0gNjIKICAgIHQgKz0gcFtpXQogICAgbiAtPSAxCiAgcmV0dXJuIHQKCnByaW50IGdlbl90b2tlbig2NCk=