code: def downgrade():
      conn = op.get_bind()
      if conn.dialect.name == "mysql":
          op.alter_column(
              table_name="variable", column_name="val", type_=mysql.TEXT
          )
  
imports: from __future__ import annotations
  from alembic import op
  from sqlalchemy.dialects import mysql
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types