first commit

utils.py

@@ -0,0 +1,14 @@
+def parse_selection(inp, max_index):
+    if inp.strip().lower() == "all":
+        return list(range(max_index))
+
+    result = set()
+    for part in inp.split(","):
+        part = part.strip()
+        if "-" in part:
+            a, b = part.split("-")
+            result.update(range(int(a) - 1, int(b)))
+        else:
+            result.add(int(part) - 1)
+
+    return sorted(i for i in result if 0 <= i < max_index)