anchor.diff:  `unit` is specified, the result will only contain transactions about this unit.
   
   + Parameters
  -    + unit (optional, string, `Gold`) ... The domain
  +    + unit (optional, string, `Gold`) ... To restrict the history to a single Unit
   
   + Request (application/json)
   
  
positive.code: 
  + Parameters
      + leaderbord (required, string) ... the board where the gamer score in
      + order (optional, string) ... the order to sort the board `hightolow` or `lowtohigh`, default is hightolow
      + type (optional, string) ... one of ["highscore", "friendscore"], default is "highscore"
      + page (optional, number) ...  th epage number or a special "me" for centered scores, default is 1
      + count (optional, number) ... the max returned rows, default is 10
  
  
  + Request (application/json)
  
negative.code: 
  + Parameters
      + friendid (required, string) ... a gamer id
      + status (required, string) ... must be one of [`add` | `forget` | `blacklist`]
  
  + Request (application/json)
  
  