APIsStandard librarycollectionsOn this pagepackagecollections Implements the collections package. Modules dict: Defines Dict, a collection that stores key-value pairs. inline_list: Defines the InlineList type. list: Defines the List type. optional: Defines Optional, a type modeling a value which may or may not be present. set: Implements the Set datatype. vector: Defines InlinedFixedVector.