/// Returns the whether `$value` is strictly equal to `false`, `null`, or the
/// string equivalent of `'false'`.
///
/// In Sass, all values other than `false` and `null` are considered truthy.
/// Sometimes, you may just want to test only for either the Bool type `false` or
/// the String equivalent of `'false'`.
///
/// @param {*} $value - A value to check.
///
/// @return {Bool} Returns `true` if `$value` is `null`, `false` or `'false'`.
///
/// @access public
/// @group Utilities
@function equals-false($value) {
  @return not not (not $value or $value == 'false');
}