Only one task In progress per assignee

rule Move to Open 
 
when State.becomes({In Progress}) && loggedInUser == Assignee { 
  var assignedIssues = loggedInUser.getIssues(Everything, "for: me"); 
   
  for each myIssue in assignedIssues { 
    if (myIssue != issue) { 
      myIssue.State = {Open}; 
    } 
  } 
}