Verify that `path` has the qpimage series file format

def verify(path):
        """Verify that `path` has the qpimage series file format"""
        valid = False
        try:
            h5 = h5py.File(path, mode="r")
            qpi0 = h5["qpi_0"]
        except (OSError, KeyError):
            pass
        else:
            if ("qpimage version" in qpi0.attrs and
                "phase" in qpi0 and
                "amplitude" in qpi0 and
                "bg_data" in qpi0["phase"] and
                    "bg_data" in qpi0["amplitude"]):
                valid = True
        return valid