The dumbdbm module is a simple DBM-style database implemented in Python. It should only be used when no other DBM database modules are available.
open(filename [, flag [, mode]])
Opens the database file filename. Note that filename should not include a suffix such as .dat or .dir. The returned database object behaves like a dictionary, as described in the “Introduction” section earlier in this chapter.
Exception raised for database-related errors other than KeyError.