Confuse is a configuration library for Python that uses YAML. It takes care of
defaults, overrides, type checking, command-line integration, environment
variable support, human-readable errors, and standard OS-specific locations.

Here is what Confuse brings to the table:
- An utterly sensible API resembling dictionary-and-list structures but
  providing transparent validation without lots of boilerplate code. Type
  config['num_goats'].get(int) to get the configured number of goats and ensure
  that it is an integer.
- Combine configuration data from multiple sources. Using layering, Confuse
  allows user-specific configuration to seamlessly override system-wide
  configuration, which in turn overrides built-in defaults. An in-package
  config_default.yaml can be used to provide bottom-layer defaults using the
  same syntax that users will see. A runtime overlay allows the program to
  programmatically override and add configuration values.
- Look for configuration files in platform-specific paths. Like $XDG_CONFIG_HOME
  or ~/.config on Unix; "Application Support" on macOS; %APPDATA% on Windows.
  Your program gets its own directory, which you can use to store additional
  data. You can transparently create this directory on demand if, for example,
  you need to initialize the configuration file on first run. And an environment
  variable can be used to override the directory's location.
- Integration with command-line arguments via argparse or optparse from the
  standard library. Use argparse's declarative API to allow command-line options
  to override configured defaults.
- Include configuration values from environment variables. Values undergo
  automatic type conversion, and nested dicts and lists are supported.
