def _create_base_string(method, base, params):
    """
    Returns base string for HMAC-SHA1 signature as specified in:
    http://oauth.net/core/1.0a/#rfc.section.9.1.3.
    """

    normalized_qs = _normalize_params(params)
    return _join_by_ampersand(method, base, normalized_qs)
Returns base string for HMAC-SHA1 signature as specified in:
    http://oauth.net/core/1.0a/#rfc.section.9.1.3.