Represents a non-overlapping interval map. By interval map, we mean a map based on an interval tree, which maps an interval (i.e., AddrRange) to a value. We currently implement this using a red-black tree, which follows the implementation of the paper written by Kimball Germane and Matthew Might: "Deletion: The Curse of the Red-Black Tree", Journal of Functional Programming, vol. 24, no. 4, 2014.