add flake.nix && and basic quadtree from file import

tests/test_quadtree.py

@@ -1,15 +1,17 @@
-
 import sys, os
-sys.path.append(os.path.realpath(os.path.dirname(__file__)+"/.."))
+
+sys.path.append(os.path.realpath(os.path.dirname(__file__) + "/.."))
 
 from src import QuadTree, TkQuadTree
 
+
 def test_sample():
     filename = "files/quadtree.txt"
     q = QuadTree.fromFile(filename)
     assert q.depth == 4
 
+
 def test_single():
     filename = "files/quadtree_easy.txt"
     q = QuadTree.fromFile(filename)
-    assert q.depth == 1
+    assert q.depth == 1