def var(<EOL>type=None,  <EOL>default=None,<EOL>name=None,<EOL>title=None,<EOL>description=None,<EOL>required=True,<EOL>examples=None,<EOL>encoder=None,<EOL>decoder=None,<EOL>min=None,  <EOL>max=None,  <EOL>unique=None,<EOL>contains=None,<EOL>**kwargs,<EOL>):
<EOL>kwargs.update(dict(default=default, type=type))<EOL>return attr.ib(<EOL>metadata={<EOL>CONFIG_KEY: _ConfigEntry(<EOL>type=type,<EOL>default=default,<EOL>name=name,<EOL>title=title,<EOL>description=description,<EOL>required=required,<EOL>examples=examples,<EOL>encoder=encoder,<EOL>decoder=decoder,<EOL>min=min,<EOL>max=max,<EOL>unique=unique,<EOL>contains=contains,<EOL>)<EOL>},<EOL>**kwargs,<EOL>)<EOL>
Creates a config variable.

    Use this method to create the class variables of your
    :func:`config <file_config._file_config.config>` decorated class.

    >>> import file_config
    >>> @file_config.config
        class MyConfig(object):
            name = file_config.var(str)

    :param type type: The expected type of the variable, defaults to None, optional
    :param default: The default value of the var, defaults to None, optional
    :param str name: The serialized name of the variable, defaults to None, optional
    :param str title: The validation title of the variable, defaults to None, optional
    :param str description: The validation description of the variable,
        defaults to None, optional
    :param bool required: Flag to indicate if variable is required during validation,
        defaults to True, optional
    :param list examples: A list of validation examples, if necessary,
        defaults to None, optional
    :param encoder: The encoder to use for the var, defaults to None, optional
    :param decoder: The decoder to use for the var, defaults to None, optional
    :param int min: The minimum constraint of the variable, defaults to None, optional
    :param int max: The maximum constraint of the variable, defaults to None, optional
    :param bool unique: Flag to indicate if variable should be unique,
        may not apply to all variable types, defaults to None, optional
    :param contains: Value that list varaible should contain in validation,
        may not apply to all variable types, defaults to None, optional
    :return: A new config variable
    :rtype: attr.Attribute