def build_extracted_list(input_list, subinterval):
    """ A utility function to extract a number of elements from a list, leaving only a certain subset.
    Generates a new list with just the subset. Creates the subset by specifying a sub-interval.
    
    :param input_list: The list to be extracted
    :type input_list: list
    :param subinterval: How many other elements to keep (for example, 10 means keep every 10 elements).
    :type subinterval: int
    :return: The extracted list.
    :rtype: list
    """
    out = []
    wait = subinterval
    for i in input_list:
        if wait == subinterval:
            out.append(i)
            wait = 0
        else:
            wait += 1
    return out