This package provides a single interface to environment variables',
configuration files', and command line arguments' provided values. The
dictionary-like interface makes interacting with these, most of the time
disparate, resources much simpler. It also allows parameters' values to be set
in any of the three sources and selects an appropriate value when a parameter's
value is specified in multiple sources. This way the most expected value,
according to the normal prcedence—command line arguments then configuration
files then environment variables, is always returned.