Abstract base class for chat memory.
ATTENTION This abstraction was created prior to when chat models had native tool calling capabilities. It does NOT support native tool calling capabilities for chat models and will fail SILENTLY if used with a chat model that has native tool calling.
DO NOT USE THIS ABSTRACTION FOR NEW CODE.
Use to keep track of the last k turns of a conversation.
If the number of messages in the conversation is more than the maximum number of messages to keep, the oldest messages are dropped.
