def pt_errors(namespace):
    """Return a sequence of strings that describe errors in the template.

        The errors may occur when the template is compiled or
        rendered.

        *namespace* is the set of names passed to the TALES expression
        evaluator, similar to what's returned by pt_getContext().

        This can be used to let a template author know what went wrong
        when an attempt was made to render the template.
        """
