Container that associates a key with multiple distinct values.
Number of distinct keys.
Number of values.
Iterate over key-value pairs.
Add a key-value pair. Values are stored in a Set, so duplicates are skipped.
count(key) after the operation.
Iterate over key and associated values.
Count values associated with a key.
List values associated with a key.
Remove a key-value pair. No-op if key-value does not exist.
count(key)
Container that associates a key with multiple distinct values.