move everything into a submodule to avoid namespace collisions

tools/aoc.py

@@ -1,8 +1,8 @@
 import os
-import tools
 from typing import List, Any, Type, Union
+from .tools import get_script_dir
 
-BASE_PATH = tools.get_script_dir()
+BASE_PATH = get_script_dir()
 INPUTS_PATH = os.path.join(BASE_PATH, 'inputs')
 
 

tools/int_seq.py

@@ -0,0 +1,5 @@
+def triangular(n: int) -> int:
+    """
+    0, 1, 3, 6, 10, 15, ...
+    """
+    return int(n * (n + 1) / 2)