code: def downgrade():
      op.add_column(
          "clusters",
          sa.Column(
              "coordinator_host", sa.String(length=256), nullable=True
          ),
      )
      op.add_column(
          "clusters",
          sa.Column("coordinator_port", sa.Integer(), nullable=True),
      )
      op.add_column(
          "clusters",
          sa.Column(
              "coordinator_endpoint",
              sa.String(length=256),
              nullable=True,
          ),
      )
  
imports: import sqlalchemy
  from alembic import op
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types