code: def _build_instance_common_args(self, ec2_keyname, availability_zone,
                                      keep_alive, hadoop_version):
          
          params = {
              'Instances.KeepJobFlowAliveWhenNoSteps' : str(keep_alive).lower(),
          }
  
          if hadoop_version:
              params['Instances.HadoopVersion'] = hadoop_version
          if ec2_keyname:
              params['Instances.Ec2KeyName'] = ec2_keyname
          if availability_zone:
              params['Instances.Placement.AvailabilityZone'] = availability_zone
  
          return params
docs: Takes a number of parameters used when starting a jobflow (as
          specified in run_jobflow() above). Returns a comparable dict for
          use in making a RunJobFlow request.