def placement_group_setup(group_name):
  """Creates placement_group group if necessary. Returns True if new placement_group
  group was created, False otherwise."""

  existing_placement_groups = u.get_placement_group_dict()

  group = existing_placement_groups.get(group_name, None)
  if group:
    assert group.state == 'available'
    assert group.strategy == 'cluster'
    print("Reusing group ", group.name)
    return group

  print("Creating group " + group_name)
  ec2 = u.get_ec2_resource()
  group = ec2.create_placement_group(GroupName=group_name, Strategy='cluster')
  return group
Creates placement_group group if necessary. Returns True if new placement_group
  group was created, False otherwise.