def input_file_to_heightmap(dir_file: str) -> list:
    """
    Args:
        dir_file (str): location of .txt file to pull data from

    Returns:
        list of lists in which each [row][col] value is the height at that position in the heightmap
    """

    with open(dir_file, "r") as file:
        content = file.read().splitlines()
        hm = []
        for index in range(len(content)):
            hm.append([])
            for num in content[index]:
                hm[index].append(int(num))
        return hm