Sets a value in a two-level nested Map structure. Creates the inner map if it doesn't exist.
Type of keys in the outer map
Type of keys in the inner map
Type of values stored in the inner maps
The outer map containing inner maps
The key for the outer map
The key for the inner map
The value to set in the inner map
The updated outer map
Sets a value in a two-level nested Map structure. Creates the inner map if it doesn't exist.