Add type hints to function signatures

For better code intelligence

tilde-train.py

@@ -43,6 +43,7 @@ from signal import signal, SIGINT
 import time ## allowing the loop steps of train animation to be slowed
 import string ## for input validation
 from inspect import cleandoc
+from pathlib import Path
 
 traincarFN = ".choochoo"
 max_x = 35  ## max length of train car.
@@ -122,16 +123,15 @@ def print_help():
 
 
 def test_user_car():
-  username = getpass.getuser()
-  fname = "/home/" + username + "/" + traincarFN
+  fname = Path.home() / traincarFN
   try:
-    myfile =  open(fname, 'r')
-  except:
-    print("ERROR: Couldn't open " + fname)
-    print("Either it doesn't exist, or is not readble by the tilde.train script.")
-    sys.exit(1)
+    choochoo_string = fname.read_text("utf-8")
+  except OSError as err:
+    raise OSError(
+      f"Couldn't open {fname}\n"
+      "Either it doesn't exist, or is not readble by the tilde.train script."
+    ) from err
 
-  choochoo_string = myfile.read()
   choochoo_list = choochoo_string.split("\n")
 
   car = "\n".join(choochoo_list)
@@ -177,27 +177,24 @@ def test_user_car():
   if train_height > max_y+1:
     print("FAIL. Your train car is too tall.")
     print("It should be no taller than " + str(max_y) + " lines in height.")
-    myfile.close()
     sys.exit(1)
 
   if train_length > max_x:
     print("FAIL. Your train car is too long.")
     print("It should be no longer than " + str(max_x) + " characters in length.")
-    myfile.close()
     sys.exit(1)
 
   print("PASS. Your train car will work on the tilde.town tracks! :)")
-  myfile.close()
   sys.exit()
 
-def link_car(car):
+def link_car(car: list[str]):
   for idx,row in enumerate(car):
     car[idx] = " " + row
   car[len(car)-3] = "+" + car[len(car)-3][1:]
   car[len(car)-2] = "+" + car[len(car)-2][1:]
   return car
 
-def validate_car(car):
+def validate_car(car: list[str]):
 ## this function (1) checks that a train car isn't too tall or too long
 ## (2) pads it vertically or on the right side if it is too short or if
 ## not all lines are the same length and (3) removes bad characters.
@@ -260,7 +257,7 @@ def print_all_cars():
 #      print "Cannot open " + fname # for debuggering purposes
 
 
-def chuggachugga(stdscr):
+def chuggachugga(stdscr: curses.window):
   curses.curs_set(0)
   h, w = stdscr.getmaxyx()
   x_pos = w-1