def make_signature(params, hmac_key):
<EOL>pairs = [x + "<STR_LIT:=>" + '<STR_LIT>'.join(params[x]) for x in sorted(params.keys()) if x != "<STR_LIT:h>"]<EOL>sha = hmac.new(hmac_key, '<STR_LIT:&>'.join(pairs), hashlib.sha1)<EOL>return base64.b64encode(sha.digest())<EOL>
Calculate a HMAC-SHA-1 (using hmac_key) of all the params except "h=".

Returns base64 encoded signature as string.