How to use the salem.wrftools.ScaledVar function in salem

if np.isscalar(c) and not isinstance(c, slice):
                item[i] = slice(c, c+1)
                squeezax.append(i)
        # add a slice in the 4th dim
        item.insert(self.ds, slice(0, self._ds_shape+1))
        item = tuple(item)

        # get data
        vars = self.nc.variables
        with ScaledVar(vars['TK']) as var:
            tk = var[item]
        with ScaledVar(vars['P']) as p, ScaledVar(vars['PB']) as pb:
            p = p[item] + pb[item]
        with ScaledVar(vars['QVAPOR']) as var:
            q = var[item]
        with ScaledVar(vars['PH']) as ph, ScaledVar(vars['PHB']) as phb:
            z = (ph[item] + phb[item]) / 9.81
        return np.squeeze(_ncl_slp(z, tk, p, q), axis=tuple(squeezax))

def __getitem__(self, item):
        with ScaledVar(self.nc.variables['PRCP_NC']) as p1, \
                ScaledVar(self.nc.variables['PRCP_C']) as p2:
            return p1[item] + p2[item]

def __getitem__(self, item):
        with ScaledVar(self.nc.variables['T']) as var:
            return var[item] + 300.

def __getitem__(self, item):

        with ScaledVar(self.nc.variables['P']) as p, \
                ScaledVar(self.nc.variables['PB']) as pb:
            res = p[item] + pb[item]
            if p.units == 'Pa':
                res /= 100
            elif p.units == 'hPa':
                pass
        return res

item = list(indexing.expanded_indexer(item, len(self.dimensions)))
        # we need the empty dims for _ncl_slp() to work
        squeezax = []
        for i, c in enumerate(item):
            if np.isscalar(c) and not isinstance(c, slice):
                item[i] = slice(c, c+1)
                squeezax.append(i)
        # add a slice in the 4th dim
        item.insert(self.ds, slice(0, self._ds_shape+1))
        item = tuple(item)

        # get data
        vars = self.nc.variables
        with ScaledVar(vars['TK']) as var:
            tk = var[item]
        with ScaledVar(vars['P']) as p, ScaledVar(vars['PB']) as pb:
            p = p[item] + pb[item]
        with ScaledVar(vars['QVAPOR']) as var:
            q = var[item]
        with ScaledVar(vars['PH']) as ph, ScaledVar(vars['PHB']) as phb:
            z = (ph[item] + phb[item]) / 9.81
        return np.squeeze(_ncl_slp(z, tk, p, q), axis=tuple(squeezax))

was_scalar = True

        # Ok, get the indexes right
        start = sl.start or 0
        stop = sl.stop or self._ds_shape
        if stop < 0:
            stop += self._ds_shape-1
        stop = np.clip(stop+1, 0, self._ds_shape)
        itemr = copy.deepcopy(item)
        if was_scalar:
            item[self.ds] = start
            itemr[self.ds] = start+1
        else:
            item[self.ds] = slice(start, stop-1)
            itemr[self.ds] = slice(start+1, stop)
        with ScaledVar(self.ncvar) as var:
            return 0.5*(var[tuple(item)] + var[tuple(itemr)])

def __getitem__(self, item):
        with ScaledVar(self.nc.variables['PRCP_NC']) as p1, \
                ScaledVar(self.nc.variables['PRCP_C']) as p2:
            return p1[item] + p2[item]