Runs a job flow
        :type name: str
        :param name: Name of the job flow
        
        :type log_uri: str
        :param log_uri: URI of the S3 bucket to place logs
        
        :type ec2_keyname: str
        :param ec2_keyname: EC2 key used for the instances
        
        :type availability_zone: str
        :param availability_zone: EC2 availability zone of the cluster
        
        :type master_instance_type: str
        :param master_instance_type: EC2 instance type of the master
        
        :type slave_instance_type: str
        :param slave_instance_type: EC2 instance type of the slave nodes
        
        :type num_instances: int
        :param num_instances: Number of instances in the Hadoop cluster
        
        :type action_on_failure: str
        :param action_on_failure: Action to take if a step terminates
        
        :type keep_alive: bool
        :param keep_alive: Denotes whether the cluster should stay
            alive upon completion
            
        :type enable_debugging: bool
        :param enable_debugging: Denotes whether AWS console debugging
            should be enabled.

        :type hadoop_version: str
        :param hadoop_version: Version of Hadoop to use. If ami_version
            is not set, defaults to '0.20' for backwards compatibility
            with older versions of boto.

        :type steps: list(boto.emr.Step)
        :param steps: List of steps to add with the job
        
        :type bootstrap_actions: list(boto.emr.BootstrapAction)
        :param bootstrap_actions: List of bootstrap actions that run
            before Hadoop starts.
            
        :type instance_groups: list(boto.emr.InstanceGroup)
        :param instance_groups: Optional list of instance groups to
            use when creating this job.
            NB: When provided, this argument supersedes num_instances
            and master/slave_instance_type.
                
        :type ami_version: str
        :param ami_version: Amazon Machine Image (AMI) version to use
            for instances. Values accepted by EMR are '1.0', '2.0', and
            'latest'; EMR currently defaults to '1.0' if you don't set
            'ami_version'.
            
        :type additional_info: JSON str
        :param additional_info: A JSON string for selecting additional features

        :type api_params: dict
        :param api_params: a dictionary of additional parameters to pass
            directly to the EMR API (so you don't have to upgrade boto to
            use new EMR features). You can also delete an API parameter
            by setting it to None.

        :rtype: str
        :return: The jobflow id

def run_jobflow(self, name, log_uri, ec2_keyname=None,
                    availability_zone=None,
                    master_instance_type='m1.small',
                    slave_instance_type='m1.small', num_instances=1,
                    action_on_failure='TERMINATE_JOB_FLOW', keep_alive=False,
                    enable_debugging=False,
                    hadoop_version=None,
                    steps=[],
                    bootstrap_actions=[],
                    instance_groups=None,
                    additional_info=None,
                    ami_version="1.0",
                    api_params=None):
        """
        Runs a job flow
        :type name: str
        :param name: Name of the job flow
        
        :type log_uri: str
        :param log_uri: URI of the S3 bucket to place logs
        
        :type ec2_keyname: str
        :param ec2_keyname: EC2 key used for the instances
        
        :type availability_zone: str
        :param availability_zone: EC2 availability zone of the cluster
        
        :type master_instance_type: str
        :param master_instance_type: EC2 instance type of the master
        
        :type slave_instance_type: str
        :param slave_instance_type: EC2 instance type of the slave nodes
        
        :type num_instances: int
        :param num_instances: Number of instances in the Hadoop cluster
        
        :type action_on_failure: str
        :param action_on_failure: Action to take if a step terminates
        
        :type keep_alive: bool
        :param keep_alive: Denotes whether the cluster should stay
            alive upon completion
            
        :type enable_debugging: bool
        :param enable_debugging: Denotes whether AWS console debugging
            should be enabled.

        :type hadoop_version: str
        :param hadoop_version: Version of Hadoop to use. If ami_version
            is not set, defaults to '0.20' for backwards compatibility
            with older versions of boto.

        :type steps: list(boto.emr.Step)
        :param steps: List of steps to add with the job
        
        :type bootstrap_actions: list(boto.emr.BootstrapAction)
        :param bootstrap_actions: List of bootstrap actions that run
            before Hadoop starts.
            
        :type instance_groups: list(boto.emr.InstanceGroup)
        :param instance_groups: Optional list of instance groups to
            use when creating this job.
            NB: When provided, this argument supersedes num_instances
            and master/slave_instance_type.
                
        :type ami_version: str
        :param ami_version: Amazon Machine Image (AMI) version to use
            for instances. Values accepted by EMR are '1.0', '2.0', and
            'latest'; EMR currently defaults to '1.0' if you don't set
            'ami_version'.
            
        :type additional_info: JSON str
        :param additional_info: A JSON string for selecting additional features

        :type api_params: dict
        :param api_params: a dictionary of additional parameters to pass
            directly to the EMR API (so you don't have to upgrade boto to
            use new EMR features). You can also delete an API parameter
            by setting it to None.

        :rtype: str
        :return: The jobflow id
        """
        # hadoop_version used to default to '0.20', but this won't work
        # on later AMI versions, so only default if it ami_version isn't set.
        if not (hadoop_version or ami_version):
            hadoop_version = '0.20'

        params = {}
        if action_on_failure:
            params['ActionOnFailure'] = action_on_failure
        params['Name'] = name
        params['LogUri'] = log_uri

        # Common instance args
        common_params = self._build_instance_common_args(ec2_keyname,
                                                         availability_zone,
                                                         keep_alive,
                                                         hadoop_version)
        params.update(common_params)

        # NB: according to the AWS API's error message, we must
        # "configure instances either using instance count, master and
        # slave instance type or instance groups but not both."
        #
        # Thus we switch here on the truthiness of instance_groups.
        if not instance_groups:
            # Instance args (the common case)
            instance_params = self._build_instance_count_and_type_args(
                                                        master_instance_type,
                                                        slave_instance_type,
                                                        num_instances)
            params.update(instance_params)
        else:
            # Instance group args (for spot instances or a heterogenous cluster)
            list_args = self._build_instance_group_list_args(instance_groups)
            instance_params = dict(
                ('Instances.%s' % k, v) for k, v in list_args.iteritems()
                )
            params.update(instance_params)

        # Debugging step from EMR API docs
        if enable_debugging:
            debugging_step = JarStep(name='Setup Hadoop Debugging',
                                     action_on_failure='TERMINATE_JOB_FLOW',
                                     main_class=None,
                                     jar=self.DebuggingJar,
                                     step_args=self.DebuggingArgs)
            steps.insert(0, debugging_step)

        # Step args
        if steps:
            step_args = [self._build_step_args(step) for step in steps]
            params.update(self._build_step_list(step_args))

        if bootstrap_actions:
            bootstrap_action_args = [self._build_bootstrap_action_args(bootstrap_action) for bootstrap_action in bootstrap_actions]
            params.update(self._build_bootstrap_action_list(bootstrap_action_args))

        if ami_version:
            params['AmiVersion'] = ami_version

        if additional_info is not None:
            params['AdditionalInfo'] = additional_info

        if api_params:
            for key, value in api_params.iteritems():
                if value is None:
                    params.pop(key, None)
                else:
                    params[key] = value

        response = self.get_object(
            'RunJobFlow', params, RunJobFlowResponse, verb='POST')
        return response.jobflowid