def is_error(value):
    """Checks if `value` is an ``Exception``.

    Args:
        value (mixed): Value to check.

    Returns:
        bool: Whether `value` is an exception.

    Example:

        >>> is_error(Exception())
        True
        >>> is_error(Exception)
        False
        >>> is_error(None)
        False

    .. versionadded:: 1.1.0
    """
    return isinstance(value, Exception)
