anchor.diff:  In case a player joins the match, the following event will be received by other players:
   
       {
  +        "type": "match.join",
           "event": {
               "_id": "548866edba0ec600005e1941",
               "match_id": "548866ed74c2e0000098db95",
  
positive.code:                 }
              ]
          },
          "id": "5007fd0a-1365-4e87-aba8-5d916731e684",
          "type": "match.leave"
      }
  
  In case the match is marked as finished, the following event will be broadcasted to all players except the one who initiated it.
  
negative.code:                 }
              ]
          },
          "id": "9155987d-6322-46d4-9403-e90ab4ba5fa3"
      }
  
  In case a player leaves the match, similarly the following event will be received by others:
  
      {
          "type": "match.leave",
          "event": {
              "_id": "548866eeba0ec600005e1948",
              "match_id": "548866ed74c2e0000098db95",
  