def decode_rle(input):
    """
    Gets a stream of data and decompresses it
    under a Run-Length Decoding.
    :param input: The data to be decoded.
    :return: The decoded string.
    """
    decode_str = ""
    count = ""

    for ch in input:
        # If not numerical
        if not ch.isdigit():
            # Expand it for the decoding
            decode_str += ch * int(count)
            count = ""
        else:
            # Add it in the counter
            count += ch
    return decode_str