# Functions
NewLocalCache returns a new LocalCache instance of the specified size and TTL.
NewMultiLevel creates and returns a new MultiLevelCache instance.
# Structs
Expired is a special type of error indicating that a key is no longer valid (value is still attached in the error).
LocalCacheImpl implements the LocalCache interface.
Miss is a special type of error indicating that a key was not found.
MultiLevelCacheImpl implements the MultiLevelCache interface.
# Interfaces
LocalCache is an in-memory TTL & LRU cache.
MLCLayer is the interface that should be implemented for all caching structs to be used with this piece of code.
MultiLevelCache bundles a list of ordered cache layers (upper -> lower).