beginner questions

[buran]

I would suggest you get back to the docs and read about isdigit(), islower() and isupper().

• str.isdigit() - Return true if all characters in the string are digits and there is at least one character, false otherwise...
  
• str.islower() - Return true if all cased characters in the string are lowercase and there is at least one cased character, false otherwise.
  
• str.isupper() - Return true if all cased characters [4] in the string are uppercase and there is at least one cased character, false otherwise.
  

What you want to check is that at least one is digit, is lowercase or is uppercase
Look at any()

Also, you raise a general Exception. I would suggest to use more appropriate ValueError