code: def list(self, request, *args, **kwargs):
          
          return super(CustomerViewSet, self).list(request, *args, **kwargs)
docs: To get a list of customers, run GET against */api/customers/* as authenticated user. Note that a user can
          only see connected customers:
  
          - customers that the user owns
          - customers that have a project where user has a role
  
          Staff also can filter customers by user UUID, for example /api/customers/?user_uuid=<UUID>
  
          Staff also can filter customers by exists accounting_start_date, for example:
  
          The first category:
          /api/customers/?accounting_is_running=True
              has accounting_start_date empty (i.e. accounting starts at once)
              has accounting_start_date in the past (i.e. has already started).
  
          Those that are not in the first:
          /api/customers/?accounting_is_running=False # exists accounting_start_date