<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def create_schema(alembic_config_ini=None):
 """Create the database schema. :param alembic_config_ini: When provided, stamp with the current revision version. """

    Base.metadata.create_all()
    if alembic_config_ini:
        from alembic.config import Config
        from alembic import command
        alembic_cfg = Config(alembic_config_ini)
        command.stamp(alembic_cfg, 'head')