code: function Relation(properties) {
              this.keys = [];
              this.vals = [];
              this.rolesSid = [];
              this.memids = [];
              this.types = [];
              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 a Relation.
  @memberof OSMPBF
  @interface IRelation
  @property {number|Long} id Relation id
  @property {Array.<number>|null} [keys] Relation keys
  @property {Array.<number>|null} [vals] Relation vals
  @property {OSMPBF.IInfo|null} [info] Relation info
  @property {Array.<number>|null} [rolesSid] Relation rolesSid
  @property {Array.<number|Long>|null} [memids] Relation memids
  @property {Array.<OSMPBF.Relation.MemberType>|null} [types] Relation types
   
  Constructs a new Relation.
  @memberof OSMPBF
  @classdesc Represents a Relation.
  @implements IRelation
  @constructor
  @param {OSMPBF.IRelation=} [properties] Properties to set