docs: def cmd_ssh_user(tar_aminame, inst_name):
      """Calculate instance login-username based on image-name.
  
      Args:
          tar_aminame (str): name of the image instance created with.
          inst_name (str): name of the instance.
      Returns:
          username (str): name for ssh based on AMI-name.
  
      """
      if tar_aminame == "Unknown":
          tar_aminame = inst_name
      # first 5 chars of AMI-name can be anywhere in AMI-Name
      userlu = {"ubunt": "ubuntu", "debia": "admin", "fedor": "root",
                "cento": "centos", "openb": "root"}
      usertemp = ['name'] + [value for key, value in list(userlu.items())
                             if key in tar_aminame.lower()]
      usertemp = dict(zip(usertemp[::2], usertemp[1::2]))
      username = usertemp.get('name', 'ec2-user')
      debg.dprint("loginuser Calculated: ", username)
      return username