Implement the basic stuff for array iterators.
Merge remote-tracking branch 'upstream/master'
Add a test case for Array's values() and keys().
Use an enum instead of strings for array iterator's type.
Remove the array kind atoms, as we use an enum now.
Improve our type check for array iterators.
Oops, had forgotten to use the simpler Get() op call.
Use an actual enum for the iterator kind.
add expected output for array30