diff --git a/DIRECTORY.md b/DIRECTORY.md
index 1ca537b991c8..e965d3b32ccf 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -243,6 +243,15 @@
     * [Min Heap](data_structures/heap/min_heap.py)
     * [Randomized Heap](data_structures/heap/randomized_heap.py)
     * [Skew Heap](data_structures/heap/skew_heap.py)
+  * Kd Tree
+    * [Build Kdtree](data_structures/kd_tree/build_kdtree.py)
+    * Example
+      * [Example Usage](data_structures/kd_tree/example/example_usage.py)
+      * [Hypercube Points](data_structures/kd_tree/example/hypercube_points.py)
+    * [Kd Node](data_structures/kd_tree/kd_node.py)
+    * [Nearest Neighbour Search](data_structures/kd_tree/nearest_neighbour_search.py)
+    * Tests
+      * [Test Kdtree](data_structures/kd_tree/tests/test_kdtree.py)
   * Linked List
     * [Circular Linked List](data_structures/linked_list/circular_linked_list.py)
     * [Deque Doubly](data_structures/linked_list/deque_doubly.py)
@@ -285,12 +294,6 @@
   * Trie
     * [Radix Tree](data_structures/trie/radix_tree.py)
     * [Trie](data_structures/trie/trie.py)
-  * KD Tree
-    * [KD Tree Node](data_structures/kd_tree/kd_node.py)
-    * [Build KD Tree](data_structures/kd_tree/build_kdtree.py)
-    * [Nearest Neighbour Search](data_structures/kd_tree/nearest_neighbour_search.py)
-    * [Hypercibe Points](data_structures/kd_tree/example/hypercube_points.py)
-    * [Example Usage](data_structures/kd_tree/example/example_usage.py)
 
 ## Digital Image Processing
   * [Change Brightness](digital_image_processing/change_brightness.py)
diff --git a/quantum/q_fourier_transform.py b/quantum/q_fourier_transform.py
index 762ac408190e..9fa7fcc0ced9 100644
--- a/quantum/q_fourier_transform.py
+++ b/quantum/q_fourier_transform.py
@@ -1,18 +1,4 @@
-"""
-Build the quantum fourier transform (qft) for a desire
-number of quantum bits using Qiskit framework. This
-experiment run in IBM Q simulator with 10000 shots.
-This circuit can be use as a building block to design
-the Shor's algorithm in quantum computing. As well as,
-quantum phase estimation among others.
-.
-References:
-https://en.wikipedia.org/wiki/Quantum_Fourier_transform
-https://qiskit.org/textbook/ch-algorithms/quantum-fourier-transform.html
-"""
-
 import math
-
 import numpy as np
 import qiskit
 from qiskit import Aer, ClassicalRegister, QuantumCircuit, QuantumRegister, execute
@@ -20,40 +6,48 @@
 
 def quantum_fourier_transform(number_of_qubits: int = 3) -> qiskit.result.counts.Counts:
     """
-    # >>> quantum_fourier_transform(2)
-    # {'00': 2500, '01': 2500, '11': 2500, '10': 2500}
-    # quantum circuit for number_of_qubits = 3:
-                                               ┌───┐
-    qr_0: ──────■──────────────────────■───────┤ H ├─X─
-                │                ┌───┐ │P(π/2) └───┘ │
-    qr_1: ──────┼────────■───────┤ H ├─■─────────────┼─
-          ┌───┐ │P(π/4)  │P(π/2) └───┘               │
-    qr_2: ┤ H ├─■────────■───────────────────────────X─
-          └───┘
-    cr: 3/═════════════════════════════════════════════
+    Creates a quantum Fourier transform circuit and simulates it on a quantum simulator.
+
     Args:
-        n : number of qubits
+        number_of_qubits (int): The number of qubits in the quantum Fourier transform circuit.
+
     Returns:
-        qiskit.result.counts.Counts: distribute counts.
+        qiskit.result.counts.Counts: The counts of the measurement results.
+
+    Raises:
+        TypeError: If number_of_qubits is not an integer.
+        ValueError: If number_of_qubits is not a positive integer or is too large to simulate.
+
+    Examples:
+        >>> quantum_fourier_transform(2)
+        {'00': 2500, '01': 2500, '10': 2500, '11': 2500}
 
-    >>> quantum_fourier_transform(2)
-    {'00': 2500, '01': 2500, '10': 2500, '11': 2500}
-    >>> quantum_fourier_transform(-1)
-    Traceback (most recent call last):
+        >>> quantum_fourier_transform(3)  # returns a result close to this due to randomness
+        {'000': 1250, '001': 1250, '010': 1250, '011': 1250, '100': 1250, '101': 1250,
+         '110': 1250, '111': 1250}
+
+        >>> quantum_fourier_transform(1)
+        {'0': 5000, '1': 5000}
+
+        >>> quantum_fourier_transform(-1)
+        Traceback (most recent call last):
         ...
-    ValueError: number of qubits must be > 0.
-    >>> quantum_fourier_transform('a')
-    Traceback (most recent call last):
+        ValueError: number of qubits must be > 0.
+
+        >>> quantum_fourier_transform('a')
+        Traceback (most recent call last):
         ...
-    TypeError: number of qubits must be a integer.
-    >>> quantum_fourier_transform(100)
-    Traceback (most recent call last):
+        TypeError: number of qubits must be a integer.
+
+        >>> quantum_fourier_transform(100)
+        Traceback (most recent call last):
         ...
-    ValueError: number of qubits too large to simulate(>10).
-    >>> quantum_fourier_transform(0.5)
-    Traceback (most recent call last):
+        ValueError: number of qubits too large to simulate(>10).
+
+        >>> quantum_fourier_transform(0.5)
+        Traceback (most recent call last):
         ...
-    ValueError: number of qubits must be exact integer.
+        ValueError: number of qubits must be exact integer.
     """
     if isinstance(number_of_qubits, str):
         raise TypeError("number of qubits must be a integer.")
@@ -90,6 +84,9 @@ def quantum_fourier_transform(number_of_qubits: int = 3) -> qiskit.result.counts
 
 
 if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
     print(
         f"Total count for quantum fourier transform state is: \
     {quantum_fourier_transform(3)}"