function manage_choropleth_props(type, props) {
  var carto_props = {
    'marker-width': props['marker-width'],
    'marker-fill-opacity': props['marker-opacity'],
    'marker-line-width': props['marker-line-width'],
    'marker-line-color': props['marker-line-color'],
    'marker-line-opacity': props['marker-line-opacity'],
    'marker-allow-overlap': props['marker-allow-overlap'],
    'line-color': props['line-color'],
    'line-opacity': props['line-opacity'],
    'line-width': props['line-width'],
    'polygon-opacity': type == "line" ? 0 : props['polygon-opacity'],
    'text-name': props['text-name'],
    'text-halo-fill': props['text-halo-fill'],
    'text-halo-radius': props['text-halo-radius'],
    'text-face-name': props['text-face-name'],
    'text-size': props['text-size'],
    'text-dy': props['text-dy'],
    'text-allow-overlap': props['text-allow-overlap'],
    'text-placement': props['text-placement'],
    'text-placement-type': props['text-placement-type'],
    'text-label-position-tolerance': props['text-label-position-tolerance'],
    'text-fill': props['text-fill']
  }

  // Remove all undefined properties
  _.each(carto_props, function(v, k){
    if(v === undefined) delete carto_props[k];
  });

  return carto_props;
}
Manage some carto properties depending on
 type (line, polygon or point), for choropleth.