some fixes

focus_sequence_FLI.py

@@ -20,6 +20,9 @@ import subprocess as sp
 
 
 def set_focus(foc_val):
+    if foc_val < 0:
+        print("INVALID FLI-FOCUSER VALUE! IT MUST BE NON-NEGATIVE VALUE!")
+        return -1
     cmd = ["fli_control", "-g", str(int(foc_val))]
     ret = sp.run(cmd, stdout=sp.PIPE, stderr=sp.PIPE)
     return ret.returncode
@@ -159,8 +162,11 @@ if __name__ == "__main__":
         focus_stop = result["focus_value"] + r
 
         if args.verbose:
-            print("\testimate guess focus position in range [{:g},{:g}]".format(focus_start, focus_stop))
-
+            print(
+                "\testimate guess focus position in range [{:g},{:g}]".format(
+                    focus_start, focus_stop
+                )
+            )
 
     if np.isfinite(args.focus_step):
         result = obsutil.focussingSequence(