def get_contig_length(dict_contig_length, contig_name):
    """
    capture the contig and their length from a dictionary
    :param dict_contig_length: dictionary of contig with their length
    :param contig_name: contig name for which we want the length
    :return: length of the contig
    """
    if contig_name in dict_contig_length.keys():
        return dict_contig_length[contig_name]
    else:
        raise KeyError("ERROR: Contig name << {} >> NOT FOUND".format(contig_name))