code: def guard_rollback_to_receive(analysis_request):
      
      skipped = 0
      valid_states = ['unassigned', 'assigned']
      skip_states = ['retracted', 'rejected']
      analyses = analysis_request.getAnalyses()
      for analysis in analyses:
          analysis = api.get_object(analysis)
          status = api.get_workflow_status_of(analysis)
          if status in valid_states:
              return True
          elif status in skip_states:
              skipped += 1
      return len(analyses) == skipped
docs: Return whether 'rollback_to_receive' transition can be performed or not.
      Returns True if the analysis request has at least one analysis in 'assigned'
      or 'unassigned' status. Otherwise, returns False