def ci_equals(left, right):
    """Check is @left string is case-insensative equal to @right string.

    :returns: left.lower() == right.lower() if @left and @right is str. Or
    left == right in other case.
    """
    if isinstance(left, str) and isinstance(right, str):
        return left.lower() == right.lower()

    return left == right