':param id: Member ID.
:type id: ``str``
:param ip: IP address of this member.
:param ip: ``str``
:param port: Port of this member
:param port: ``str``
:param balancer: Balancer this member is attached to. (optional)
:param balancer: :class:`.LoadBalancer`
:param extra: Provider specific attributes.
:type extra: ``dict``'

def __init__(self, id, ip, port, balancer=None, extra=None):

    self.id = (str(id) if id else None)
    self.ip = ip
    self.port = port
    self.balancer = balancer
    self.extra = (extra or {})
