def METHOD_NAME(fileNames,sl,ymin=-15.,ymax=15.):
    option = "HISTOP"
    colors = (2,4,9,12,38,44,46,55)
    markers = (24,25,26,27,28,30,32,5)
    idx = 0
    canvases = [None,None]
    objects = None
    histoRef = None
    histos = []
    histosDist = []
    for fileName in fileNames:
        objs = plot(fileName,sl,300,360,'',False)
        histos.append( objs[1].Clone(objs[1].GetName() + "_diff") )
        histos[-1].SetName( "%s_%d" % (histos[-1].GetName(),idx) )
        if not idx:
            histoRef = objs[1]
            histos[-1].Reset()
        else:
            histos[-1].Add(histoRef,-1.) 
        draw = False
        if not idx: draw = True
        objs = drawHisto(histos[-1],
                         title="t_{Trig} difference (ns)",
                         ymin=ymin,ymax=ymax,option=option,draw=draw)
        if not idx: 
            canvases[0] = objs[0]
            objects = objs[2]
        if idx:
            canvases[0].cd()
            histos[-1].SetLineColor(colors[ (idx - 1) % len(colors) ])
            histos[-1].SetMarkerColor(colors[ (idx - 1) % len(colors) ])
            histos[-1].SetMarkerStyle(markers[ (idx - 1) % len(markers) ])
            histos[-1].Draw(option + "SAME")
            histosDist.append( ROOT.TH1F(histos[-1].GetName() + "_dist","tTrig distribution",200,ymin,ymax) )
            for ibin in range(1,histos[-1].GetNbinsX()+1):
                histosDist[-1].Fill( histos[-1].GetBinContent(ibin) )
            histosDist[-1].SetLineColor(colors[ (idx - 1) % len(colors) ])
            histosDist[-1].SetMarkerColor(colors[ (idx - 1) % len(colors) ])
            histosDist[-1].SetMarkerStyle(markers[ (idx - 1) % len(markers) ])
        idx += 1
    canvases[1] = ROOT.TCanvas("c_tTrigDist")
    canvases[1].SetGridy()
    canvases[1].SetFillColor(0)
    canvases[1].cd()
    option = "HISTO"
    idx = 0
    for histo in histosDist:
        if not idx:
            histo.GetXaxis().SetTitle("t_{Trig} difference (ns)")
            histo.GetYaxis().SetTitle("Number of chambers")
            histo.Draw(option)
        else:
            histo.Draw(option + "SAME") 
        idx += 1
    return (canvases,histos,histosDist,objects)