code: def upgrade():
      op.add_column(
          "report_schedule",
          sa.Column(
              "report_format",
              sa.String(length=50),
              server_default="PNG",
              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