Contents distinguisher. This tells objects apart based on their nominal contents (and only applies to objects with nominal contents at all). Note that we're interested in the *names* of the contents, so even if two objects have different contents objects, they're still considered equal if the contents' names match. (E.g., two "buckets of water" are indistinguishable, even if the contents are two distinct "water" objects. But "bucket of water" and "bucket of fish" are distinguishable.)

contentsDistinguisher :   Distinguisher