Completed part1 and part2

part-1.py

@@ -4,17 +4,42 @@
 # the appropriate comment.
 
 # factorial
+def factorial(n):
+    if n < 0:
+        raise ValueError("Factorial is not defined for negative numbers.")
 
+    if n == 0 or n == 1:
+        return 1
+
+    result = n * factorial(n - 1)
+    return result
 
 
 # reverse
+def reverse(text):
+    if len(text) <= 1:
+        return text
 
+    result = text[-1] + reverse(text[:-1])
+    return result
 
 
 # bunny
+def bunny(count):
+    if count < 0:
+        raise ValueError("The count of bunny should not be negative.")
+    if count == 0:
+        return 0
 
+    count = 2 + bunny(count - 1)
+    return count
 
 
 # is_nested_parens
-
-
+def is_nested_parens(parens):
+    if len(parens) == 0:
+        return True
+    if parens[0] != "(" or parens[-1] != ")":
+        return False
+    result = is_nested_parens(parens[1:-1])
+    return result

part-2.py

@@ -4,13 +4,31 @@
 # the appropriate comment.
 
 # search
-
+def search(array, query):
+    if not array:
+        return False
+    if array[0] == query:
+        return True
+    return search(array[1:], query)
 
 
 # is_palindrome
-
+def is_palindrome(text):
+    if len(text) <= 1:
+        return True
+    if text[0] != text[-1]:
+        return False
+    return is_palindrome(text[1:-1])
 
 
 # digit_match
+def digit_match(n, m):
+    if n == 0 and m == 0:
+        return 1
+
+    count = 1 if n % 10 == m % 10 else 0
 
+    if n < 10 or m < 10:
+        return count
 
+    return count + digit_match(n // 10, m // 10)