code: def upgrade():
      op.add_column(
          "dbs", sa.Column("allow_ctas", sa.Boolean(), nullable=True)
      )
      op.add_column(
          "dbs",
          sa.Column("expose_in_sqllab", sa.Boolean(), nullable=True),
      )
      op.add_column(
          "dbs",
          sa.Column(
              "force_ctas_schema", sa.String(length=250), nullable=True
          ),
      )
  
imports: import sqlalchemy
  from alembic import op
label_desc: Use image node_id 1 for calling a global function with example usage: upgrade() without return types