old_contents: #!/usr/bin/env python
  ''' yamlcfg.util
  
  Cross module utilities
  '''
  import os
  
  def normalize(var, type=None, **kwargs):
      if var is None:
          return None
      if type is None:
          return var
      if type is basestring:
          return str(type)
      elif type is int:
          return int(type)
      elif type is hex:
          return int(type, 16)
      elif type is bin:
          return int(type, 2)
      elif type is oct:
          return int(type, 8)
      else:
          raise ValueError('Unrecognized type argument. '
              'Cannot normalize variable.')
  
  def validate_ext(path, valid_ext):
      path, ext = os.path.splitext(path)
      if ext.startswith('.'):
          ext = ext[1:].lower()
      if isinstance(valid_ext, basestring):
          return ext == valid_ext.lower()
      elif hasattr(valid_ext, '__contains__'):
          return ext in {x.lower() for x in valid_ext}
      else:
          raise ValueError('valid_ext must be either a string or implement '
              '__contains__')
  
new_contents: #!/usr/bin/env python
  ''' yamlcfg.util
  
  Cross module utilities
  '''
  import os
  
  def normalize(var, type=None, **kwargs):
      if var is None:
          return None
      if type is None:
          return var
      if type is basestring:
          return str(type)
      elif type is int:
          return int(type)
      elif type is hex:
          return int(type, 16)
      elif type is bin:
          return int(type, 2)
      elif type is oct:
          return int(type, 8)
      else:
          raise ValueError('Unrecognized type argument. '
              'Cannot normalize variable.')
  
  def validate_ext(path, valid_ext):
      path, ext = os.path.splitext(path)
      if ext.startswith('.'):
          ext = ext[1:].lower()
      if isinstance(valid_ext, basestring):
          return ext == valid_ext.lower()
      elif hasattr(valid_ext, '__contains__'):
          return ext in [x.lower() for x in valid_ext]
      else:
          raise ValueError('valid_ext must be either a string or implement '
              '__contains__')
  
subject: change set comp in case python 2.6