contract Dispatcher {

  // Functions.
  constructor (address contractAddress) {}
  function initialize() returns (bool result);
  function replace(address newContract) returns (address newAddress);
  function double(uint256 multiplicand) returns (uint256 product);
  function halve(uint256 dividend) returns (uint256 quotient);

  // Events.
  event Initialized(bool result);
  event Replaced(address indexed oldAddress, address newAddress);
  event Doubled(uint256 product);
  event Halved(uint256 quotient);

}