anchor.diff:  * Any two `NaN` values are equivalent (both directly or inside nested structures).
   * However, `null` and `NaN` values are not equivalent (both directly or inside nested structures).
   
  -<<equivalence-def,Equivalence>> is reflexive for all values.
  +Equivalence is reflexive for all values.
   
   [[aggregation]]
   === Aggregation ===
  
positive.code:   For exampe, `{a: 1} \<= {a: 1, b: null}` evaluates to `null`.
    ** Regular maps are <<incomparable>> to any value that is not also a regular map.
    * Nodes
    ** The comparison order for nodes is unspecified and left to implementations.
    ** Nodes are <<incomparable>> to any value that is not also a node.
    * Relationships
    ** The comparison order for relationships is unspecified and left to implementations.
    ** Relationships are <<incomparable>> to any value that is not also a relationship.
  - Paths
    ** Paths are compared as if they were a list of alternating nodes and relationships of the path from the start node to the end node.
  
negative.code: 
  [horizontal]
  [[comparability-con,comparability (concept)]]*Comparability*:: <<comparability-def,Comparability>> is used by the inequality operators (`>`, `<`, `>=`, `\<=`), and defines the underlying semantics of how to compare two values.
  [[equality-con,equality (concept)]]*Equality*:: <<equality-def,Equality>> is used by the equality operators (`=`, `<>`), and the list membership operator (`IN`).
  It defines the underlying semantics to determine if two values are the same in these contexts.
  Equality is also used implicitly by literal maps in node and relationship patterns, since such literal maps are merely a shorthand notation for equality predicates.
  [[orderability-con,orderability (concept)]]*Orderability*:: <<orderability-def,Orderability>> is used by the `ORDER BY` clause, and defines the underlying semantics of how to order values.
  [[equivalence-con,equivalence (concept)]]*Equivalence*:: <<equivalence-def,Equivalence>> is used by the `DISTINCT` modifier and by grouping in projection clauses (`WITH`, `RETURN`), and defines the underlying semantics to determine if two values are the same in these contexts.
  