<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def init(db_url, alembic_ini=None, debug=False, create=False):
 """ Create the tables in the database using the information from the url obtained. :arg db_url, URL used to connect to the database. The URL contains information with regards to the database engine, the host to connect to, the user and password and the database name. ie: <engine>://<user>:<password>@<host>/<dbname> :kwarg alembic_ini, path to the alembic ini file. This is necessary to be able to use alembic correctly, but not for the unit-tests. :kwarg debug, a boolean specifying wether we should have the verbose output of sqlalchemy or not. :return a session that can be used to query the database. """

    engine = create_engine(db_url, echo=debug)

    if create:
        BASE.metadata.create_all(engine)

    # This... "causes problems"
    #if db_url.startswith('sqlite:'):
    #    def _fk_pragma_on_connect(dbapi_con, con_record):
    #        dbapi_con.execute('pragma foreign_keys=ON')
    #    sa.event.listen(engine, 'connect', _fk_pragma_on_connect)

    if alembic_ini is not None:  # pragma: no cover
        # then, load the Alembic configuration and generate the
        # version table, "stamping" it with the most recent rev:
        from alembic.config import Config
        from alembic import command
        alembic_cfg = Config(alembic_ini)
        command.stamp(alembic_cfg, "head")

    scopedsession = scoped_session(sessionmaker(bind=engine))
    return scopedsession