title: Where is hosts.txt that parallel-ssh uses
body: <p>this might sound silly but I'm really stuck here...</p>
  
  <p>I want parallel-ssh to preform operations on multiple hosts and I know I have to put their IPs in file hosts.txt, but where is this fabled hosts.txt file? Or if I have to create it, where? Because I keep getting this: </p>
  
  <p>IOError: [Errno 2] No such file or directory: 'hosts.txt'</p>