text: import os
  from logging.config import fileConfig
  
  from alembic import context
  from sqlalchemy import engine_from_config, pool
  
  import stoma.models
  from pym.rc import Rc
  
  # this is the Alembic Config object, which provides
  # access to the values within the .ini file in use.
  config = context.config
  
  # Interpret the config file for Python logging.
  # This line sets up loggers basically.
  fileConfig(config.config_file_name)
  
  # add your model's MetaData object here
  # for 'autogenerate' support
  # from myapp import mymodel
  # target_metadata = mymodel.Base.metadata
  target_metadata = stoma.models.DbBase.metadata
  
  # other values from the config, defined by the needs of env.py,
  # can be acquired:
  # my_important_option = config.get_main_option("my_important_option")
  # ... etc.
  
  PYM_ENV = config.get_main_option("environment")
  if not PYM_ENV:
      raise KeyError('Missing key "environment" in config.')
  # The directory of the config file is our root_dir
  rc = Rc(environment=PYM_ENV,
      root_dir=os.path.normpath(
          os.path.join(os.path.dirname(__file__), '..', '..', '..')
      )
  )
  rc.load()
  
  
  def run_migrations_offline():
      """Run migrations in 'offline' mode.
  
      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 = rc.g('db.stoma.sa.url')
      context.configure(
          url=url,
          target_metadata=target_metadata,
          compare_type=True,
          compare_server_default=True
      )
  
      with context.begin_transaction():
          context.run_migrations(rc=rc)
  
  
  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 = engine_from_config(
          rc.data,
          prefix='db.pym.sa.',
          poolclass=pool.NullPool
      )
  
      connection = engine.connect()
      context.configure(
          connection=connection,
          target_metadata=target_metadata,
          compare_type=True,
          compare_server_default=True
      )
  
      try:
          with context.begin_transaction():
              context.run_migrations(rc=rc)
      finally:
          connection.close()
  
  if context.is_offline_mode():
      run_migrations_offline()
  else:
      run_migrations_online()
  