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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:
 async def fromURL( cls, url, *, credentials=None, insecure=False):
 """Return a `SessionAPI` for a given MAAS instance."""

        try:
            description = await helpers.fetch_api_description(
                url, insecure=insecure)
        except helpers.RemoteError as error:
            # For now just re-raise as SessionError.
            raise SessionError(str(error))
        else:
            session = cls(description, credentials)
            session.insecure = insecure
            return session