//  getSponsoringCount(): returns the number of points _sponsor is
    //                        providing service to
    //
    function getSponsoringCount(uint32 _sponsor)
      view
      external
      returns (uint256 count)
    {
      return sponsoring[_sponsor].length;
    }

    //  getSponsoring(): returns a list of points _sponsor is providing
    //                   service to
    //
    //    Note: only useful for clients, as Solidity does not currently
    //    support returning dynamic arrays.
    //
    function getSponsoring(uint32 _sponsor)
      view
      external
      returns (uint32[] sponsees)
    {
      return sponsoring[_sponsor];
    }

  //  sponsoring: per point, the points they are sponsoring
  //
  mapping(uint32 => uint32[]) public sponsoring;

  //  sponsoringIndexes: per point, per point, (index + 1) in
  //                     the sponsoring array
  //
  mapping(uint32 => mapping(uint32 => uint256)) public sponsoringIndexes;