text: from sfa.util.enumeration import Enum
  
  # recognized top level rspec elements
  RSpecElements = Enum('NETWORK', 'NODE', 'SLIVER', 'INTERFACE', 'LINK', 'VLINK')
  
  class RSpecElement:
      def __init__(self, element_type, name, path):
          if not element_type in RSpecElements:
              raise InvalidRSpecElement(element_type)
          self.type = element_type
          self.name = name
          self.path = path
  