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ballot.sol

pragma solidity ^0.4.0;
contract Hub {
    function contribute(address _address) payable returns (address) {
       Project project = Project(_address);
       project.fund.value(msg.value)(msg.sender);
       return msg.sender;
    }
}

contract Project {
    uint amount;
    mapping (address => uint) public contributors;
    
    function fund(address sender) payable {
        amount += msg.value;
        contributors[sender] = msg.value;
    }
}