Add some comments, and make improvement number one: - always allow nil to be casted to any atom, because   * it would be impossible to insert nil for that atom otherwise   * conversion from nil to nil should be trivial
Add some comments, and make improvement number one:
- always allow nil to be casted to any atom, because
  * it would be impossible to insert nil for that atom otherwise
  * conversion from nil to nil should be trivial

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb