from typing import List


def join_sublist_element(input_list: List[List[str]]) -> List[str]:
    """Join each sublist of chars into string.

    This function joins all the element(chars) in each sub-lists together, and
    turns every sub-lists to one element in the overall list.
    The sublist will turned into a string with all the same elements as before.
    :param input_list: the returned list after cut
    :return: the list that contains all the segments as strings.
    """

    return ["".join(chars) for chars in input_list]