'Return a string that contains the parameters that must be signed.'

def get_normalized_parameters(self):

    params = dict(self.parameters)
    try:
        del params['oauth_signature']
    except:
        pass
    key_values = [(escape(_utf8_str(k)), escape(_utf8_str(v))) for (k, v) in params.items()]
    key_values.sort()
    return '&'.join([('%s=%s' % (k, v)) for (k, v) in key_values])
