"Let me explain. No, there is too much. Let me sum up." ~ Inigo Montoya
Inigos are simple sequences which experience loss of information with time. They are append-only and grow logarithmically in size with their input, instead of linearly, discarding information as they grow.
Inigo is available under the Apache 2.0 license; see LICENSE for details.
The name of the library and data structure goes to Allen Short, who also provided the classic movie quote.
David Barbour's explanation of the possible uses of inigos inspired me to provide a Python implementation. His article is at http://awelonblue.wordpress.com/2013/01/24/exponential-decay-of-history-improved/ and is worth reading.