Signing with EDDSA (curve25519) throws AttributeError: _coord_size

[aptly-io]

Trying to sign with EDDSA as below returns me an Exception.
Is there someone who can explain what I do wrong?

(I'm using 1.2.5 on python3 3.7.5)

from ecpy.curves import Curve,Point
from ecpy.keys import ECPublicKey, ECPrivateKey
from ecpy.eddsa import EDDSA
from ecpy.ecrand import rnd
from hashlib import blake2b

curve = Curve.get_curve('Curve25519') # Montgomery with size 256

priv_key = rnd(curve.order)

pv_key = ECPrivateKey(priv_key, curve)

hasher = blake2b()
signer = EDDSA(hasher)

sig = signer.sign(b'Lorem ipsu', pv_key)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/francis/dev/projects/edge/venv37-imx/lib/python3.7/site-packages/ecpy/eddsa.py", line 118, in sign
    return self._do_sign(msg, pv_key)
  File "/home/francis/dev/projects/edge/venv37-imx/lib/python3.7/site-packages/ecpy/eddsa.py", line 125, in _do_sign
    size = curve._coord_size()
  File "/home/francis/dev/projects/edge/venv37-imx/lib/python3.7/site-packages/ecpy/curves.py", line 120, in __getattr__
    raise AttributeError(name)
AttributeError: _coord_size

I assume one has to use the Ed25519 instead of Curve25519 ...

[aptly-io]

This project does EdDSA with Ed25519 and blake2b correctly: https://github.com/Matoking/python-ed25519-blake2b

[cslashm]

You cannot use 'Curve25519' with eddsa, you have to use 'Ed25519'
Curve25519 is for DH, Ed25519 is for signing.
I should add a check in the builder.