code: def generate_login(self, min_length=6, max_length=10, digits=True):
          
          chars = string.ascii_lowercase
          if digits:
              chars += string.digits
          length = random.randint(min_length, max_length)
          return ''.join(random.choice(chars) for x in range(length))
docs: Generate string for email address login with defined length and
          alphabet.
  
          :param min_length: (optional) min login length.
          Default value is ``6``.
          :param max_length: (optional) max login length.
          Default value is ``10``.
          :param digits: (optional) use digits in login generation.
          Default value is ``True``.