secp256k1 – Question on Coincident Python Library / libsecp256k

I am a noob with cryptography, I just try to learn using python and coincurve library ( which is a mature Python link for libsecp256k1.

The following code creates a private key and produces a signature of the string "Hello world!".

pk = coincurve.PrivateKey ()
message = b "this is a test!"
s = pk.sign_recoverable (message)

Signature s is a sequence of 65 bytes.

The signature is recoverable: I can extract the public key from pk of s.

pub = pk.public_key
pub2 = coincurve.PublicKey.from_signature_and_message (s, message)
assert (pub == pub2)

Until here everything is fine! However, I do not understand how to use the verification method. The following code

valid = coincurve.verify_signature (s, message, pub)

gives the following error:

ValueError: the signature encoded in DER could not be parsed.

So the problem is that the method verify_signature is waiting for a signature in DER format. This is normally produced using the sign method as opposed to the signer_recouvrable method:

t = pk.sign (message)
valid = coincurve.verify_signature (t, message, pub.format ())

that works well.

So my question is:

QUESTION: How to change from "DER" format to "recoverable" format in the Python library?