def create_roi(name, left, right, bgr_width=3, address='', _larch=None):
    return ROI(name=name, left=left, right=right,
               bgr_width=bgr_width, address=address)
create an ROI, a named portion of an MCA spectra defined by index
dataset/ETHPy150Open xraypy/xraylarch/plugins/xrf/roi.py/create_roi