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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 create(self):
 """Create this database within its instance Inclues any configured schema assigned to :attr:`ddl_statements`. See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.CreateDatabase :rtype: :class:`~google.api_core.operation.Operation` :returns: a future used to poll the status of the create request :raises Conflict: if the database already exists :raises NotFound: if the instance owning the database does not exist """

        api = self._instance._client.database_admin_api
        metadata = _metadata_with_prefix(self.name)
        db_name = self.database_id
        if "-" in db_name:
            db_name = "`%s`" % (db_name,)

        future = api.create_database(
            parent=self._instance.name,
            create_statement="CREATE DATABASE %s" % (db_name,),
            extra_statements=list(self._ddl_statements),
            metadata=metadata,
        )
        return future