def METHOD_NAME(file_lo, file_hi):
    # we'll wait until we find the L1 data
    lines_lo = []
    found_l1 = False
    with open(file_lo, "r") as flo:
        for line in flo:
            if "L1 norm" in line:
                found_l1 = True
                continue
            if not found_l1:
                continue
            # value data lines have 4 columns
            if len(line.split()) == 4:
                lines_lo.append(line.strip())
    lines_hi = []
    found_l1 = False
    with open(file_hi, "r") as fhi:
        for line in fhi:
            if "L1 norm" in line:
                found_l1 = True
                continue
            if not found_l1:
                continue
            # value data lines have 4 columns
            if len(line.split()) == 4:
                lines_hi.append(line.strip())
    cd = ConvergenceData()
    for llo, lhi in zip(lines_lo, lines_hi):
        vlo, elo, o1, emed1 = llo.split()
        vhi, emed2, o2, ehi = lhi.split()
        if "---" in o1 or "---" in o2:
            print("skipping {}".format(vlo))
            continue
        if vlo != vhi:
            sys.exit("error: variable mismatch")
        if emed1.strip() != emed2.strip():
            print(emed1, emed2)
            sys.exit("error: error mismatch")
        cd.add_variable(vlo, elo, o1, emed1, o2, ehi)
    return cd