def import_gff3(filepath):
    """
    This function opens a GFF3-file in the location specified by the
    variable 'filepath'. Looping over the file, the list variable
    'feature_list' will be used to store short lists of DNA features.
    This 2D list is returned.
    :param filepath: string containing the location of the GFF3-file.
    :return feature_list: a 2D list containing DNA features, their
        type, start position, end position, coding strand and
        translation frame.
    """
    feature_list = []
    with open(filepath, 'r') as infile:
        iterdata = iter(infile.readlines())
        next(iterdata)
        for line in iterdata:
            line = line.strip("\n").split("\t")
            feature_list.append([line[0], line[2], int(line[3]), int(line[4]), line[5], line[6], line[-1]])
    return feature_list