@classmethod
def from_boto_dict(cls, listener) ->'ELBListener':
    """
        Instantiates a `ELBListener` object from the dictionary returned
        by boto3.
        """
    protocol = listener['Protocol']
    load_balancer_port = listener['LoadBalancerPort']
    instance_protocol = listener['InstanceProtocol']
    instance_port = listener['InstancePort']
    ssl_certificate_id = listener.get('SSLCertificateId')
    return cls(protocol, load_balancer_port, instance_protocol,
        instance_port, ssl_certificate_id)
