function showHideLayer(layerName) {
  new_style = (document.getElementById(layerName).style.display == "none") ? "block" : "none";
  document.getElementById(layerName).style.display = new_style;
}

function hideLayer(layerName) {
  document.getElementById(layerName).style.display = 'none';
}

function showLayer(layerName) {
  document.getElementById(layerName).style.display = 'block';
}

function change_layer(layer_name) {
  var mn=window.document.getElementsByTagName('div');
  for (var i=0;i<window.document.getElementsByTagName('div').length;i++) {
    var a=window.document.getElementsByTagName('div')[i].style.display="none";
  }
document.getElementById(layer_name).style.display = 'block';
}