Database.ml : Unified interfaces of stored data for Camomile
read dir suffix reader key reads information using reader.
Data are supposed to reside in the files under dir directory
with suffix suffix. reader takes in_channel as an argument
and read data from in_channel. The key specifies key associated
the value. Any characters can be used in key, since they are
properly escaped. If there are no data associated to key, raise
Not_found.
writer dir suffix writer key data write data associated the
key into the directory dir with suffix. You can use
any characters in key since they are propery escaped.