/*
   * Get Covenant by index
   *
   * The index is just a convenience access method and
   * does NOT imply any preference/ordering of the Covenants.
   *
   * The solver always considers Covenants as a set.
   *
   * call-seq:
   *  solver.get_covenant(1) -> Covenant
   *
   */
  Covenant *get_covenant( unsigned int i )