anchor.diff:  
   Returns an array of *Group* objects representing all groups which '$user' is a member of.
   
  +
  +=== Instance methods
  +
  +==== addMember(User $user) : void
  +
  +Adds '$user' to the group in the database.
  +
  +
  +==== getMembers() : array
  +
  +Returns an array of *User* objects representing the group's members.
  +
  +
  +==== containsMember(User $user) : bool
  +
  +Returns *true* if group contains '$user', otherwise *false*.
  +
  +
  +==== removeMember(User $user) : void
  +
  +Removes '$user' from the group in the database.
  +
  +
  +=== Static methods
   
   ==== setupDB() : void
   
  
positive.code: for more details.
  
  
  ==== getAll() : array
  
  Returns an array of *Group* objects representing all groups in the database.
  
negative.code: Returns the unique *id* of the group.
  
  
  === Group Management
  
  ==== __construct(int $id)
  
  