code: def downgrade():
      with op.batch_alter_table(
          "trial_intermediate_values"
      ) as batch_op:
          batch_op.alter_column(
              "intermediate_value", type_=Float, nullable=False
          )
      with op.batch_alter_table("trial_params") as batch_op:
          batch_op.alter_column(
              "param_value", type_=Float, existing_nullable=True
          )
      with op.batch_alter_table("trial_values") as batch_op:
          batch_op.alter_column(
              "value", type_=Float, existing_nullable=False
          )
  
file_path: optuna/optuna/storages/_rdb/alembic/versions/v3.0.0.b.py
imports: import enum
  from alembic import op
  from sqlalchemy import and_
  from sqlalchemy import Column
  from sqlalchemy import Enum
  from sqlalchemy import Float
  from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy.orm import Session
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types