def __init__(self,<EOL>file_env_var: str = None,<EOL>default_files: List[str] = None,<EOL>load: bool = False):
self.file_env_var = file_env_var<EOL>self.config_file = None<EOL>self.default_files = default_files or []<EOL>if load:<EOL><INDENT>self.load()<EOL><DEDENT>
:param file_env_var: the name of an environment variable which can be
                     used for the name of the configuration file to
                     load
:param default_files: if no file is given, try to load a configuration
                      from these files in order
:param load: load config file on instantiation [default: False].

A docstring defined on the class should be a plain-text description
used as a header when generating a configuration file.