Minor edit

b_asic/signal_generator.py

@@ -183,7 +183,10 @@ class FromFile(SignalGenerator):
             self._data = data
             self._len = len(data)
         except ValueError:
-            raise Exception("Selected input file is not of the right format.")
+            raise Exception(
+                "Selected input file is not of the right format, should be of filetype"
+                " .txt or .csv and contain single column input vector."
+            )
 
     def __call__(self, time: int) -> complex:
         if 0 <= time < self._len: