Provides a time-efficient method for searching for values in some specified key field in large files that are sorted on that key field.
The program uses a binary search method.
Fields may be specified as delimited of fixed column values within a record.
This program can exhaust your RAM pretty easily if you pass it a huge file. Python 2.x
handles huge files less well than Python 3.x (difference in mmap implementation?).
Some desktop Linux distros to not apply ulimits for memory usage at all, and so this program could easily crash your user session if you pass it a huge file!