code: function AttributionControl(controlDiv) {
    // Set CSS for the control border.
    let controlUI = document.createElement('div');
    controlUI.style.backgroundColor = '#fff';
    controlUI.style.opacity = '0.7';
    controlUI.style.border = '2px solid #fff';
    controlUI.style.cursor = 'pointer';
    controlDiv.appendChild(controlUI);
  
    // Set CSS for the control interior.
    let controlText = document.createElement('div');
    controlText.style.color = 'rgb(25,25,25)';
    controlText.style.fontFamily = 'Roboto,Arial,sans-serif';
    controlText.style.fontSize = '10px';
    controlText.innerHTML = ATTR;
    controlUI.appendChild(controlText);
    return controlDiv;
  }
docs: now add an attribution control. in real life you might add CSS classes instead of setting the style here.