base64 = Base.url_encode64(url, @base64_opts)
sig = :crypto.hmac(:sha, secret, base64)
sig64 = sig |> Base.url_encode64(@base64_opts)
base64 = Base.url_encode64(url, @base64_opts)
sig = :crypto.hmac(:sha, secret, base64)
sig64 = sig |> Base.url_encode64(@base64_opts)