'Start a task using random placement and the default Amazon ECS
scheduler. If you want to use your own scheduler or place a
task on a specific container instance, use `StartTask`
instead.
:type cluster: string
:param cluster: The short name or full Amazon Resource Name (ARN) of
the cluster that you want to run your task on. If you do not
specify a cluster, the default cluster is assumed..
:type task_definition: string
:param task_definition: The `family` and `revision` (
`family:revision`) or full Amazon Resource Name (ARN) of the task
definition that you want to run.
:type overrides: dict
:param overrides:
:type count: integer
:param count: The number of instances of the specified task that you
would like to place on your cluster.'

def run_task(self, task_definition, cluster=None, overrides=None, count=None):

    params = {'taskDefinition': task_definition}
    if (cluster is not None):
        params['cluster'] = cluster
    if (overrides is not None):
        params['overrides'] = overrides
    if (count is not None):
        params['count'] = count
    return self._make_request(action='RunTask', verb='POST', path='/', params=params)
