This document tries to explain how we have to handle maps in Go code because it's a bit special.
See also #105
Maps have to be passed by a pointer to both Store and Load methods.
This is different from structs where Store takes a *Foo and Load takes **Foo.
In Go a map value, under the hood, is a pointer.
However, we don't have access to that pointer (without using hacks that depend on internals of the runtime/compiler, which might change in the future).
One result of that is that Go only allows to compare map value to a nil but not to another map.
The only way to have a stable reference to a map is to use a pointer to it.
This is similar to taking a pointer to a struct but it does look weird.