code: def add_workflow_definitions(sbi_config: dict):
      
      registered_workflows = []
      for i in range(len(sbi_config['processing_blocks'])):
          workflow_config = sbi_config['processing_blocks'][i]['workflow']
          workflow_name = '{}:{}'.format(workflow_config['id'],
                                         workflow_config['version'])
          if workflow_name in registered_workflows:
              continue
          workflow_definition = dict(
              id=workflow_config['id'],
              version=workflow_config['version'],
              stages=[]
          )
          key = "workflow_definitions:{}:{}".format(workflow_config['id'],
                                                    workflow_config['version'])
          DB.save_dict(key, workflow_definition, hierarchical=False)
          registered_workflows.append(workflow_name)
docs: Add any missing SBI workflow definitions as placeholders.
  
      This is a utility function used in testing and adds mock / test workflow
      definitions to the database for workflows defined in the specified
      SBI config.
  
      Args:
          sbi_config (dict): SBI configuration dictionary.