def METHOD_NAME(histos):
    rel_diff = 0
    if len(histos)>0:
        for ib in range(0, histos[0].GetNbinsX()):
            for ih, h in enumerate(histos):
                if not ih == 0:
                    if not histos[0].GetBinContent(ib+1) == 0:
                        rel_diff+=((h.GetBinContent(ib+1)-histos[0].GetBinContent(ib+1))/histos[0].GetBinContent(ib+1))*((h.GetBinContent(ib+1)-histos[0].GetBinContent(ib+1))/histos[0].GetBinContent(ib+1))
    return math.sqrt(rel_diff)