add w2lists_def readout

Add function to automatically read out w2list_XXX_idx from definitions for an offline file

src/km3io/tools.py

@@ -556,3 +556,13 @@ def get_w2list_idx(f):
     sim_program = f.header.simul.program.lower()
     return w2s_idx.get(sim_program)
 
+
+def is_nanobeacon(trigger_mask):
+    """Returns True if the trigger mask contains the nano-beacon flag.
+
+    Parameters
+    ----------
+    trigger_mask : int or array(int)
+      A value or an array of the trigger_mask, either of an event, or a hit.
+    """
+    return is_bit_set(trigger_mask, ktrg.JTRIGGERNB)