How to use the check50.Error function in check50

def check_pyramid(output, correct):
    if output == correct:
        return

    err = Error((output, correct))
    output = output.split("\n")
    correct = correct.split("\n")

    # check for trailing whitespace
    if len(output) == len(correct) and all(ol.rstrip() == cl for ol, cl in zip(output, correct)):
        err.helpers = "Did you add too much trailing whitespace to the end of your pyramid?"
    raise err

def wait(self, timeout=5):
        try:
            self.child.expect(EOF, timeout=timeout)
        except TIMEOUT:
            e = Error("timed out while waiting for program to exit")
            e.__context__ = TIMEOUT(timeout)
            raise e
        except UnicodeDecodeError:
            raise Error("output not valid ASCII text")

        self.kill()

        if self.child.signalstatus == signal.SIGSEGV:
            raise Error("failed to execute program due to segmentation fault")

        self.exitstatus = self.child.exitstatus
        return self

def wait(self, timeout=5):
        try:
            self.child.expect(EOF, timeout=timeout)
        except TIMEOUT:
            e = Error("timed out while waiting for program to exit")
            e.__context__ = TIMEOUT(timeout)
            raise e
        except UnicodeDecodeError:
            raise Error("output not valid ASCII text")

        self.kill()

        if self.child.signalstatus == signal.SIGSEGV:
            raise Error("failed to execute program due to segmentation fault")

        self.exitstatus = self.child.exitstatus
        return self

def __init__(self, test, path):
        dir, file = os.path.split(path)
        name, _ = os.path.splitext(file)

        # add directory of flask app to sys.path so we can import it properly
        prevpath = sys.path[0]
        try:
            sys.path[0] = os.path.abspath(dir or ".")
            mod = imp.load_source(name, file)
        except (OSError, IOError) as e:
            if e.errno == errno.ENOENT:
                e = Error("could not find {}".format(file))
            raise e
        finally:
            # restore sys.path
            sys.path[0] = prevpath

        try:
            app = mod.app
        except AttributeError:
            raise Error("{} does not contain an app".format(file))

        # initialize flask client
        app.testing = True
        self.client = app.test_client()

        self.test = test
        self.response = None

def exit(self, code=None, timeout=5):
        self.wait(timeout)

        if code is None:
            return self.exitstatus

        self.test.log.append("checking that program exited with status {}...".format(code))
        if self.exitstatus != code:
            raise Error("expected exit code {}, not {}".format(code, self.exitstatus))
        return self

def _send(self, method, route, data, params, **kwargs):
        """Send request of type `method` to `route`"""
        route = self._fmt_route(route, params)
        self.test.log.append("sending {} request to {}".format(method.upper(), route))

        try:
            self.response = getattr(self.client, method.lower())(route, data=data, **kwargs)
        except BaseException as e:  # Catch all exceptions thrown by app
            # TODO: Change Finance starter code for edX and remove this as well as app.testing = True in __init__
            self.test.log.append("exception raised in application: {}: {}".format(type(e).__name__, e))
            raise Error("application raised an exception (see log for details)")

        return self