code: def password_validator(self, form, field):
          
  
          # Convert string to list of characters
          password = list(field.data)
          password_length = len(password)
  
          # Count lowercase, uppercase and numbers
          lowers = uppers = digits = 0
          for ch in password:
              if ch.islower(): lowers += 1
              if ch.isupper(): uppers += 1
              if ch.isdigit(): digits += 1
  
          # Password must have one lowercase letter, one uppercase letter and one digit
          is_valid = password_length >= 6 and lowers and uppers and digits
          if not is_valid:
              raise ValidationError(
                  _('Password must have at least 6 characters with one lowercase letter, one uppercase letter and one number'))
docs: Ensure that passwords have at least 6 characters with one lowercase letter, one uppercase letter and one number.
  
          Override this method to customize the password validator.