public void AddClaim(Claim claim)
 {
     for (var i = claim.Left; i < claim.Right; ++i)
     {
         for (var j = claim.Top; j < claim.Bottom; ++j)
         {
             foreach (var conflictingClaim in canvas[i, j])
             {
                 claim.ConflictsWith(conflictingClaim);
             }
             canvas[i, j].Add(claim);
         }
     }
 }