docs: function createWorldFile(x0, y0, res) {
    let halfPxInM = res / 2.0;
    let ret = res + '\n';
    ret += '0.0' + '\n';
    ret += '0.0' + '\n';
    ret += '-' + res + '\n';
    ret += x0 + halfPxInM + '\n';
    ret += y0 - halfPxInM;
    return ret;
  }