Allow load_dark to load an array of dark images

src/toolbox_scs/detectors/hrixs.py

@@ -5,7 +5,7 @@ import matplotlib.pyplot as plt
 from scipy.optimize import leastsq
 from scipy.optimize import curve_fit
 from scipy.signal import fftconvolve
-
+import xarray as xr
 import toolbox_scs as tb
 
 
@@ -323,7 +323,15 @@ class hRIXS:
         return data
 
     def load_dark(self, runNB, proposal=None):
-        data = self.from_run(runNB, proposal)
+        try:
+            # Checks to see if runNB can be iterated over (is list-like)
+            data_list = []
+            for run in runNB:
+                data_list.append(self.from_run(run, proposal))
+            data = xr.concat(data_list, dim='trainId') 
+        except TypeError:
+            # If runNB cannot be iterated over, we assume it's a single run
+            data = self.from_run(runNB, proposal)
         self.dark_image = data['hRIXS_det'].mean(dim='trainId')
         self.USE_DARK = True