desc: These tests test the type of command
tests:

    # Method form
    - py: r.expr(None).type_of()
      js: r(null).typeOf()
      rb: r(nil).type_of()
      ot: "'NULL'"

    # Prefix form
    - py: r.type_of(None)
      js: r.typeOf(null)
      rb: r.type_of(nil)
      ot: "'NULL'"

    # Error cases
    - js: r(null).typeOf(1)
      ot: err('RqlDriverError', 'Expected 0 argument(s) but found 1.', [0])
