code: function ArrayType(typeSpec) {
    if (!typeSpec.subtype) {
      console.error('Array.typeSpec is missing subtype. Assuming string.' +
          JSON.stringify(typeSpec));
      typeSpec.subtype = 'string';
    }
  
    Object.keys(typeSpec).forEach(function(key) {
      this[key] = typeSpec[key];
    }, this);
    this.subtype = types.getType(this.subtype);
  }
docs: A set of objects of the same type