code: function ExtensionRange(properties) {
                      if (properties)
                          for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                              if (properties[keys[i]] != null)
                                  this[keys[i]] = properties[keys[i]];
                  }
docs: Properties of an ExtensionRange.
  @memberof google.protobuf.DescriptorProto
  @interface IExtensionRange
  @property {number|null} [start] ExtensionRange start
  @property {number|null} [end] ExtensionRange end
   
  Constructs a new ExtensionRange.
  @memberof google.protobuf.DescriptorProto
  @classdesc Represents an ExtensionRange.
  @implements IExtensionRange
  @constructor
  @param {google.protobuf.DescriptorProto.IExtensionRange=} [properties] Properties to set