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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 import_db(filename=None):
 """ Imports the database. Make sure that you have this in your ``~/.pgpass`` file: localhost:5433:*:publishizer_publishizer:publishizer Also make sure that the file has ``chmod 0600 .pgpass``. Usage:: fab import_db fab import_db:filename=foobar.dump """

    local_machine()
    if not filename:
        filename = settings.DB_DUMP_FILENAME
    with fab_settings(warn_only=True):
        local('pg_restore -O -c -U {0}{1} -d {2} {3}'.format(
            env.db_role, HOST, env.db_name, filename))