code: function addType(typeName, type) {
  	if (types[typeName]) {
  		throw new Error("Type already registered '" + typeName + "'");
  	}
  	types[typeName] = type;
  }
docs: Adds a type
  
  @param {string} typeName unique identifier for the type
  @param {Object} type
  @throws {Error} if duplicate with same name was found