code: def de_camel(s, separator="_", _lowercase=True):
      
      s = re.sub(r"([a-z0-9])([A-Z])", "\\1%s\\2" % separator, s)
      s = re.sub(r"([A-Z])([A-Z][a-z])", "\\1%s\\2" % separator, s)
      return s.lower() if _lowercase else s
docs: Returns the string with CamelCase converted to underscores, e.g.,
          de_camel("TomDeSmedt", "-") => "tom-de-smedt"
          de_camel("getHTTPResponse2) => "get_http_response2"