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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 to_database(self, manager=None):
 """Send the model to the PyBEL database This function wraps :py:func:`pybel.to_database`. Parameters manager : Optional[pybel.manager.Manager] A PyBEL database manager. If none, first checks the PyBEL configuration for ``PYBEL_CONNECTION`` then checks the environment variable ``PYBEL_REMOTE_HOST``. Finally, defaults to using SQLite database in PyBEL data directory (automatically configured by PyBEL) Returns ------- network : Optional[pybel.manager.models.Network] The SQLAlchemy model representing the network that was uploaded. Returns None if upload fails. """

        network = pybel.to_database(self.model, manager=manager)
        return network