Do day 3.

d4.py

@@ -0,0 +1,40 @@
+import re
+
+EXAMPLE = """
+
+"""
+
+def clean(text: str) -> list[str]:
+    return list(filter(lambda l: l.strip() != "", text.splitlines()))
+
+def solve(lines: list[str]):
+    s = 0
+    for (i, line) in enumerate(lines):
+        print(i, line)
+    return s
+
+def solve2(lines: list[str]):
+    s = 0
+    for (i, line) in enumerate(lines):
+        print(i, line)
+    return s
+
+def main():
+    example = clean(EXAMPLE)
+    print("Example  1:", solve(example))
+    return
+
+    data = clean(open("i4.txt").read())
+    print("Solution 1:", solve(data))
+    return
+
+    example = clean(EXAMPLE)
+    print("Example  2:", solve2(example))
+    return
+
+    data = clean(open("i4.txt").read())
+    print("Solution 2:", solve2(data))
+    return
+
+if __name__ == "__main__":
+    main()