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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def errorstr(self, space, use_repr=False):
        "The exception class and value, as a string."
        w_value = self.get_w_value(space)
        if space is None:
            # this part NOT_RPYTHON
            exc_typename = str(self.w_type)
            exc_value = str(w_value)
        else:
            w = space.wrap
            if space.is_w(space.type(self.w_type), space.w_text):
                exc_typename = space.str_w(self.w_type)
            else:
                exc_typename = space.str_w(
                    space.getattr(self.w_type, w('__name__')))
            if space.is_w(w_value, space.w_None):
                exc_value = ""
            else:
                try:
                    if use_repr:
                        exc_value = space.str_w(space.repr(w_value))
                    else:
                        exc_value = space.str_w(space.str(w_value))
                except OperationError:
                    # oups, cannot __str__ the exception object
                    exc_value = "<oups, exception object itself cannot be str'd>"
        if not exc_value:
            return exc_typename
        else:
            return '%s: %s' % (exc_typename, exc_value)