def join_bpe(lst:list, s:str):
    """Join words together that are prefaced with '##'. To be used with `reduce` """

    if s[:2] == "##":
        # How to handle situation where first term is double hashed?
        base = lst.pop() # Remove from last position
        new_term = base + s.strip("#")
        return lst + [new_term]
    return lst + [s]