anchor.diff:  
   This might produce something like `[:Foo/Bar :Baz/7]`.  The numeric id
   will be generated by the Datastore - see
  -[Assigning identifiers](https://cloud.google.com/appengine/docs/java/datastore/entities#Java_Assigning_identifiers).
  +link:https://cloud.google.com/appengine/docs/java/datastore/entities#Java_Assigning_identifiers[Assigning identifiers].
   
   
   # keys and the datastore
  
positive.code: 
  Used as a query specification, this would match all Entities having
  kind `:Genus` and having parent Key `Subfamily("Felinae")` - the
  family [Felinae](https://en.wikipedia.org/wiki/Felinae) includes, in
  addition to genus _Felis_, _Leopardus_, _Lynx_, _Puma_, and several
  others, so this might match `[:Subfamily/Felinae :Genus/Felis]`,
  `[:Subfamily/Felinae :Genus/Leopardus]`, etc.
  
negative.code: ancestor path), use ds/key-name.  ("name" is reserved for getting the
  name component of a Key node).
  
  (Note that the keys in a keychain need not be associated with actual Entities in the datastore.)
  
  Migae uses keywords to encode Kinds and Identifiers.  The native
  datastore uses String for Kinds, and either String or Long for
  