TODO

TODO
----
  * Add POST form parsing. This is sort of stubbed out right now and
    should be supported.

  * Add locking around sqlite transactions so that write operations can
    be considered vaguely safe.

  * Support for insert queries that return the inserted row ID from
    SQLite and MySQL. Not required for Postgres or Cockroach because
    they allow selecting last inserted ID as part of an insert.

    Both MySQL and SQLite may be able to work around this right now by
    setting an isolation level to get a transaction, assuming that
    selecting the last inserted ID works with multiple transactions (in
    MySQL's case -- in SQLite's case, there can only be one).

  * Better support for accessing previous-query results without the need
    for full `expr` arguments.
    
  * Consider replacing YAML and JSON with codf, which would allow the
    use of multi-line raw strings.

  * Add support for upstream HTTP servers as a data source, with the
    ability to make HTTP queries to upstream servers from input data.
    Maybe also support POST requests somehow? TBD how this would work
    but it would make for a very flexible translation server.

  * Add support for upstream HTTP servers as a data source, with the
    ability to make HTTP queries to upstream servers from input data.
    Maybe also support POST requests somehow? TBD how this would work
    but it would make for a very flexible translation server.

  * Add no-query form to query steps so folks can do stuff like
    transform the input body or set up other data between steps.