def get_sub_indices(seq, sub_seq):
    """
    Compute indices of where the first element of sub sequence locates in the sequence.
    :param seq: a sequence(list, str, tuple and so on) like:
        ["a", "b", "c", "b", "c"]
    :param sub_seq:
        ["b", "c"]
    :return: a list of indices, where the first element of sub sequence locates in the sequence, like:
        [1, 3]
    """
    indices_list = []
    seq_length, sub_seq_length = len(seq), len(sub_seq)
    for i in range(seq_length):
        if seq[i:i+sub_seq_length] == sub_seq:
            indices_list.append(i)
    return indices_list