Buying Token contract

FCMP2.sol

pragma solidity ^0.4.17;

/*
  Copyright 2017, FastCashMoneyPlus.biz
  This contract is for educational purposes only, and is presented WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED.
*/

contract FastCashMoneyPlus {
  uint public totalSupply;
  uint256 public fastCashBank;
  address public centralBanker;
  
  uint public decimals = 18;
  string public name = "FastCashMoneyPlus";
  mapping (address => uint) public balanceOf;
  
  function FastCashMoneyPlus() {
    totalSupply = 1000000 * 10 ** uint256(decimals);
    fastCashBank = totalSupply;
    centralBanker = msg.sender;
  }
  
  function weiToMoneyBucks(uint _wei) returns (uint) {
    return _wei * 2;
  }
  
  function buy() payable returns (uint) {
    uint _wei = msg.value;

    uint _moneyBucks = weiToMoneyBucks(_wei);

    require(_moneyBucks > 0);
    require(fastCashBank >= _moneyBucks);

    balanceOf[msg.sender] += _moneyBucks;
    fastCashBank -= _moneyBucks;

    centralBanker.transfer(msg.value);

    return _moneyBucks;
  }
  
  function transfer(address _to, uint _amount) public returns (bool success) {
    address _from = msg.sender;
    
    require(_to != address(0));
    require(_to != address(this));
    require(_amount > 0);
    require(balanceOf[_from] >= _amount);
    require(balanceOf[_to] + _amount > balanceOf[_to]);

    balanceOf[_from] -= _amount;
    balanceOf[_to] += _amount;

    return true;
  }
}