code: public static File find(OperaProduct product) {
      File binary = findBinaryBasedOnEnvironmentVariable();
      if (binary != null) {
        return binary;
      }
      return findBinaryBasedOnPlatform(product);
    }
docs: Locate the binary of the given product on the local system.  If no binary is found, null is
  returned.
  
  Some products, such as {@link OperaProduct#DESKTOP} offers multiple configurations of the same
  product (Opera and Opera Next), in which case the first is preferred.
  
  @param product the product to find the binary of
  @return the binary of the product, or null