How to use the alembic.context.run_migrations function in alembic

directives[:] = []
                logger.info('No changes in schema detected.')

    engine = engine_from_config(config.get_section(config.config_ini_section),
                                prefix='sqlalchemy.',
                                poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(connection=connection,
                      target_metadata=target_metadata,
                      process_revision_directives=process_revision_directives,
                      **current_app.extensions['migrate'].configure_args)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()

This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    version_table = config.get_main_option("version_table")
    context.configure(url=url, version_table=version_table)

    with context.begin_transaction():
        context.run_migrations()

we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        version_table='zerqu_alembic_version',
    )

    with context.begin_transaction():
        context.run_migrations()

logger.info('No changes in schema detected.')

    engine = engine_from_config(config.get_section(config.config_ini_section),
                                prefix='sqlalchemy.',
                                poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(compare_type=True,
                      connection=connection,
                      target_metadata=target_metadata,
                      process_revision_directives=process_revision_directives,
                      **current_app.extensions['migrate'].configure_args)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()

def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.
    """
    engine = api.get_engine()
    with engine.connect() as connection:
        context.configure(connection=connection,
                          render_as_batch=True,
                          target_metadata=target_metadata)
        with context.begin_transaction():
            context.run_migrations()

directives[:] = []
                logger.info('No changes in schema detected.')

    engine = engine_from_config(alembic_config,
                                prefix='sqlalchemy.',
                                poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(connection=connection,
                      target_metadata=db.metadata,
                      compare_type=True,
                      process_revision_directives=process_revision_directives)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()

LOGGER.info('No changes in schema detected.')

    engine = engine_from_config(config.get_section(config.config_ini_section),
                                prefix='sqlalchemy.',
                                poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(connection=connection,
                      target_metadata=target_metadata,
                      process_revision_directives=process_revision_directives,
                      compare_type=True,
                      **current_app.extensions['migrate'].configure_args)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()

This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url, target_metadata=target_metadata, literal_binds=True
    )

    with context.begin_transaction():
        context.run_migrations()

directives[:] = []
                logger.info('No changes in schema detected.')

    engine = engine_from_config(config.get_section(config.config_ini_section),
                                prefix='sqlalchemy.',
                                poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(connection=connection,
                      target_metadata=target_metadata,
                      process_revision_directives=process_revision_directives,
                      **current_app.extensions['migrate'].configure_args)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()