This library supports the reading and writing of structured data using
the "JavaScript Object Notation" (JSON).  This format is specified by
RFC 426 (http://tools.ietf.org/html/rfc4627).

There are two levels of I/O supported.  The "stream" level supports
event-based parsing (e.g., like a SAX parser for XML) and output at
the same level.  Use this mode to extract small amounts of information
from large files or when you want to directly build your own representation
of the file.  The "file" level supports a "DOM-style" approach that reads/writes
trees (see json.sml for the representation).