diff --git a/testing_project/logistic.py b/testing_project/logistic.py
index cb3e06e..f5b0957 100644
--- a/testing_project/logistic.py
+++ b/testing_project/logistic.py
@@ -2,3 +2,10 @@
 
 def f(x, r):
     return r * x * (1-x) 
+
+def iterate_f(it, x, r):
+    result = [x]
+    for i in range(it):
+        x = f(x, r)
+        result.append(x)
+    return result
diff --git a/testing_project/test_logistic.py b/testing_project/test_logistic.py
index c2ece9f..d68934d 100644
--- a/testing_project/test_logistic.py
+++ b/testing_project/test_logistic.py
@@ -1,6 +1,6 @@
 from numpy.testing import assert_allclose
 import pytest
-from logistic import f
+from logistic import f, iterate_f
 
 
 @pytest.mark.parametrize('x,r,expected', [(0, 1.1, 0),(1, 3.7, 0)])
@@ -34,3 +34,11 @@ def test_f_normal_cases():
 # x=0.1, r=2.2, it=1 => iterate_f(it, x, r)=[0.1, 0.198]
 # x=0.2, r=3.4, it=4 => iterate_f(it, x, r)=[0.2, 0.544, 0.843418, 0.449019, 0.841163]
 # x=0.5, r=2, it=3 => iterate_f(it, x, r)=[0.5, 0.5, 0.5]
+@pytest.mark.parametrize('x,r,it,expected', [
+    (0.1, 2.2, 1, [0.1, 0.198]),
+    (0.2, 3.4, 4, [0.2, 0.544, 0.843418, 0.449019, 0.841163]),
+    (0.5, 2, 3, [0.5, 0.5, 0.5, 0.5]),
+])
+def test_iterate_f(x, r, it, expected):
+    result = iterate_f(it, x, r)
+    assert_allclose(result, expected, rtol=1e-06)