of the elliptic curve, as defined in the `ECC table`_.

  d (integer):
    Mandatory for a private key and a NIST P-curve (e.g., P-256):
    the integer in the range ``[1..order-1]`` that represents the key.

  seed (bytes):
    Mandatory for a private key and an EdDSA curve.
    It must be 32 bytes for Ed25519, and 57 bytes for Ed448.

  point_x (integer):
    Mandatory for a public key: the X coordinate (affine) of the ECC point.

  point_y (integer):
    Mandatory for a public key: the Y coordinate (affine) of the ECC point.

Returns:
  :class:`EccKey` : a new ECC key object
r°