def METHOD_NAME(folder_id, creds=None):
    """Return all projects under a folder.
    Args:
        folder_id: str, folder id.
        creds: obj, service_account.Credentials objects.
    Yields:
        Project, object.
    """
    filter_str = 'parent.type:folder parent.id:%s lifecycleState:ACTIVE'
    projects = _paginate_projects(filter_str % folder_id, creds)
    for project in projects:
        yield project