code: def login_user_block(username, ssh_keys, create_password=True):
      
      block = {
          'create_password': 'yes' if create_password is True else 'no',
          'ssh_keys': {
              'ssh_key': ssh_keys
          }
      }
  
      if username:
          block['username'] = username
  
      return block
docs: Helper function for creating Server.login_user blocks.
  
      (see: https://www.upcloud.com/api/8-servers/#create-server)