function(
    a,    // The array containing the points of the snake
    b,    // The next step snake head should move to
    c,    // The apple position
    d,    // The size of the level
    e    // Just declaration
    ) {
       a.unshift(b);                                    // Move the head of the snake forward
       c^a[0]&&a.pop();                                 // If we don't hit apple, decrement snake tail
       for(b=d*d;b--;)                                  // Loop through level
          e=[e]+"■ "[!~a.indexOf(b)&b!=c]+["\n"[b%d]];  // Put space or snake(or apple) body, and line end if needed
       return~a.indexOf(a[0],1)||e                     // Return rendered level as string, or a number if game is over
}