Take a look at the docs:

http://dlang.org/hash-map.html

Under the Properties table, byKey is listed as:

`.byKey()` - Note the parens here. We never noticed this code as a problem because we never had strict property enforcement.

One other thing to mention about that table, it's called a "Property" table, but it doesn't actually mean `@property` functions, instead it means "methods of AA". Otherwise the `.get` method would not be there, because it is not (and cannot be) a `@property` function.

Anyway, we need to remove `@property` from byKey and byValue or we'll end up breaking a ton of code for no benefit. Perhaps we should also stop using the word `Property` in the docs when refering to regular methods, because it's confusing. Ping @andralex for thoughts.