code: def upgrade():
      op.add_column(
          "datasources",
          sa.Column(
              "fetch_values_from", sa.String(length=100), nullable=True
          ),
      )
      op.add_column(
          "tables",
          sa.Column(
              "fetch_values_predicate",
              sa.String(length=1000),
              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