code: def _normalize_field_name(value):
      
      # Replace non word/letter character
      return_value = re.sub(r'[^\w\s-]+', '', value)
      # Replaces whitespace with underscores
      return_value = re.sub(r'\s+', '_', return_value)
      return return_value.lower()
docs: Normalizing value string used as key and field name.
  
      :param value: String to normalize
      :type value: str
  
      :return: normalized string
      :rtype: str