contract Bitcoin {
/// @return total amount of tokens
 function totalSupply() constant returns (uint256 supply) {}
/// @param _owner The address from which the balance will be retrieved
 /// @return The balance
 function balanceOf(address _owner) constant returns (uint256 balance) {}
/// @notice send `_value` token to `_to` from `msg.sender`
 /// @param _to The address of the recipient
 /// @param _value The amount of token to be transferred
 /// @return Whether the transfer was successful or not
 function transfer(address _to, uint256 _value) returns (bool success) {}
/// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
 /// @param _from The address of the sender
 /// @param _to The address of the recipient
 /// @param _value The amount of token to be transferred
 /// @return Whether the transfer was successful or not
 function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}
/// @notice `msg.sender` approves `_addr` to spend `_value` tokens
 /// @param _spender The address of the account able to transfer the tokens
 /// @param _value The amount of wei to be approved for transfer
 /// @return Whether the approval was successful or not
 function approve(address _spender, uint256 _value) returns (bool success) {}
/// @param _owner The address of the account owning tokens
 /// @param _spender The address of the account able to transfer the tokens
 /// @return Amount of remaining tokens allowed to spent
 function allowance(address _owner, address _spender) constant returns (uint256 remaining) {}
event Transfer(address indexed _from, address indexed _to, uint256 _value);
 event Approval(address indexed _owner, address indexed _spender, uint256 _value);
 
}
function approve(address _spender, uint256 _value) returns (bool success) {}

/// @notice `msg.sender` approves `_addr` to spend `_value` tokens
/// @param _spender The address of the account able to transfer the tokens
/// @param _value The amount of wei to be approved for transfer
/// @return Whether the approval was successful or not