def get_annotation_class(annotation_class_name):
    """ Get Annotation class matching provided name

    Args:
        annotation_class_name (str): Name of annotation class.

    Returns:
        Annotation class with data structure and function(s) for finding
        overlaps
    """
    if annotation_class_name == 'htseq':
        from ._annotation_htseq import _AnnotationHTSeq
        return _AnnotationHTSeq
    elif annotation_class_name == 'intervaltree':
        from ._annotation_intervaltree import _AnnotationIntervalTree
        return _AnnotationIntervalTree
    else:
        raise NotImplementedError('Choices are "htseq" or "intervaltree".')
