def __init__(self, name, is_required=True, default_val=None,<EOL>filters=None, help_txt=None):
self.name = name<EOL>self.is_required = is_required<EOL>self.default_val = default_val<EOL>self.filters = filters or []<EOL>self.help_txt = help_txt<EOL>
:param str name: The name of the environment variable. *This is
    case-sensitive!*
:keyword bool is_required: If ``True``, this variable must be defined
    when your Python process starts. If ``False``, the default loaded
    value will match ``default_val``.
:keyword default_val: If ``is_required`` is ``False`` and this
    environment variable is not defined, this value will be loaded.
:keyword list filters: A list of functions to pass the environment
    variable's value (or default value) through. Order is
    significant!
:keyword str help_txt: Optional help text describing the environment
    variable.