contract WalletAbi {
  // Revokes a prior confirmation of the given operation
  function revoke(bytes32 _operation) external;

  // Replaces an owner `_from` with another `_to`.
  function changeOwner(address _from, address _to) external;

  function addOwner(address _owner) external;

  function removeOwner(address _owner) external;

  function changeRequirement(uint _newRequired) external;

  function isOwner(address _addr) constant returns (bool);

  function hasConfirmed(bytes32 _operation, address _owner) external constant returns (bool);

  // (re)sets the daily limit. needs many of the owners to confirm. doesn't alter the amount already spent today.
  function setDailyLimit(uint _newLimit) external;

  function execute(address _to, uint _value, bytes _data) external returns (bytes32 o_hash);
  function confirm(bytes32 _h) returns (bool o_success);
}
function changeOwner(address _from, address _to) external;
// Replaces an owner `_from` with another `_to`.