contract PricingStrategy {

  /** Interface declaration. */
  function isPricingStrategy() public constant returns (bool) {
    return true;
  }

  /** Self check if all references are correctly set.
   *
   * Checks that pricing strategy matches crowdsale parameters.
   */
  function isSane(address crowdsale) public constant returns (bool) {
    return true;
  }

  /**
   * When somebody tries to buy tokens for X eth, calculate how many tokens they get.
   *
   *
   * @param value - What is the value of the transaction send in as wei
   * @param tokensSold - how much tokens have been sold this far
   * @param weiRaised - how much money has been raised this far
   * @param msgSender - who is the investor of this transaction
   * @param decimals - how many decimal units the token has
   * @return Amount of tokens the investor receives
   */
  function calculatePrice(uint value, uint tokensSold, uint weiRaised, address msgSender, uint decimals) public constant returns (uint tokenAmount);
}
/**
 * Interface for defining crowdsale pricing.
 */
function isSane(address crowdsale) public constant returns (bool) {
    return true;
  }
/** Self check if all references are correctly set.
 *
 * Checks that pricing strategy matches crowdsale parameters.
 */