'Constructor.
:keyword    name: Name of the key pair object.
:type       name: ``str``
:keyword    fingerprint: Key fingerprint.
:type       fingerprint: ``str``
:keyword    public_key: Public key in OpenSSH format.
:type       public_key: ``str``
:keyword    private_key: Private key in PEM format.
:type       private_key: ``str``
:keyword    extra: Provider specific attributes associated with this
key pair. (optional)
:type       extra: ``dict``'

def __init__(self, name, public_key, fingerprint, driver, private_key=None, extra=None):

    self.name = name
    self.fingerprint = fingerprint
    self.public_key = public_key
    self.private_key = private_key
    self.driver = driver
    self.extra = (extra or {})
