p>Indexed types are linear lists of elements than can be accessed in constant time
with an integer index.  Indexed types are backed by a single chunk of memory for
fast access, and are indexed from 0 as in C.  Dictionary types associate keys
with values. The difference between dictionaries and indexed types is that
dictionaries are not limited to integer keys. They are backed by a hash table
and also offer constant time lookup (and insertion for the mutable case).
Finally, the 'bytes' abstraction is any typ