Add ANSI colored output

fibonacci.py

@@ -1,5 +1,11 @@
 #!/usr/bin/env python3
-"""Fibonacci sequence calculator."""
+"""Fibonacci sequence calculator with colored output."""
+
+# ANSI color codes
+GREEN = "\033[32m"
+CYAN = "\033[36m"
+RED = "\033[31m"
+RESET = "\033[0m"
 
 
 def fibonacci(n: int) -> int:
@@ -34,8 +40,8 @@ if __name__ == "__main__":
     try:
         n = int(sys.argv[1])
     except ValueError:
-        print(f"Error: '{sys.argv[1]}' is not a valid integer")
+        print(f"{RED}Error: '{sys.argv[1]}' is not a valid integer{RESET}")
         sys.exit(1)
     
     result = fibonacci(n)
-    print(f"fibonacci({n}) = {result}")
+    print(f"{CYAN}fibonacci({n}){RESET} {GREEN}={RESET} {GREEN}{result}{RESET}")