code: def none_to_blank(s, exchange=''):
      
      if isinstance(s, list):
          return [none_to_blank(z) for y, z in enumerate(s)]
      return exchange if s is None else unicode(s)
docs: Replaces NoneType with ''
  
      >>> none_to_blank(None, '')
      ''
      >>> none_to_blank(None)
      ''
      >>> none_to_blank('something', '')
      u'something'
      >>> none_to_blank(['1', None])
      [u'1', '']
  
      :param s: String to replace
      :para exchange: Character to return for None, default is blank ('')
      :return: If s is None, returns exchange