Minor usability improvements

terminal_ui.py

@@ -1,14 +1,20 @@
+from typing import Optional
+
+
 def query(text):
     return input(f"{text} \n> ")
 
 
-def query_int(text):
+def query_int(text: str, default: Optional[int] = None):
     try:
         ans = query(text)
-        return int(ans)
+        if ans or default is None:
+            return int(ans)
+        else:
+            return default
     except ValueError:
         print("Please enter a valid number!")
-        return query_int(text)
+        return query_int(text, default)
 
 
 def query_yes_no(question, default="yes"):