def detectSignature(filename):
    # the list contains all the accesses
    rlist = AccList()
    wlist = AccList()
    accList = AccList()  # all lines with "accList" are commentted out
                          # because the figure drawing using accList
                          # is replaced with rlist and wlist

    # open the trace file
    f = open(filename, 'r')

    # skip the first several lines
    # Maybe the skipped lines are table heads
    for i in range(int(sig._format_prop['skip_lines'])):
        line = f.readline()