'Constructor.
Args:
scenario: [SpinnakerTestScenario] The scenario being supported.'

def __init__(self, scenario):

    super(AwsScenarioSupport, self).__init__('aws', scenario)
    self.__aws_observer = None
    bindings = scenario.bindings
    if (not bindings['AWS_IAM_ROLE']):
        bindings['AWS_IAM_ROLE'] = scenario.agent.deployed_config.get('providers.aws.defaultIAMRole', None)
    if (not bindings['TEST_AWS_ZONE']):
        bindings['TEST_AWS_ZONE'] = bindings['AWS_ZONE']
    if (not bindings.get('TEST_AWS_REGION', '')):
        bindings['TEST_AWS_REGION'] = bindings['TEST_AWS_ZONE'][:(-1)]
    if (not bindings.get('TEST_AWS_KEYPAIR', '')):
        bindings['TEST_AWS_KEYPAIR'] = '{0}-keypair'.format(bindings['SPINNAKER_AWS_ACCOUNT'])
    bindings.add_lazy_initializer('TEST_AWS_VPC_ID', self.__lazy_binding_initializer)
    bindings.add_lazy_initializer('TEST_AWS_SECURITY_GROUP_ID', self.__lazy_binding_initializer)
