text: """
  docstring needed
  
  :copyright: Copyright 2010-2017 by the NineML Python team, see AUTHORS.
  :license: BSD-3, see LICENSE for details.
  """
  from ....componentclass.visitors.validators import (
      AliasesAreNotRecursiveComponentValidator,
      NoUnresolvedSymbolsComponentValidator,
      CheckNoLHSAssignmentsToMathsNamespaceComponentValidator)
  from ..base import BaseConnectionRuleVisitor
  
  
  class AliasesAreNotRecursiveConnectionRuleValidator(
          AliasesAreNotRecursiveComponentValidator,
          BaseConnectionRuleVisitor):
  
      """Check that aliases are not self-referential"""
  
      pass
  
  
  class NoUnresolvedSymbolsConnectionRuleValidator(
          NoUnresolvedSymbolsComponentValidator,
          BaseConnectionRuleVisitor):
      """
      Check that aliases and timederivatives are defined in terms of other
      parameters, aliases, statevariables and ports
      """
      pass
  
  
  class CheckNoLHSAssignmentsToMathsNamespaceConnectionRuleValidator(
          CheckNoLHSAssignmentsToMathsNamespaceComponentValidator,
          BaseConnectionRuleVisitor):
  
      """
      This class checks that there is not a mathematical symbols, (e.g. pi, e)
      on the left-hand-side of an equation
      """
      pass
  