diff --git a/src/array_utils.py b/src/array_utils.py
new file mode 100644
index 00000000..a0906b75
--- /dev/null
+++ b/src/array_utils.py
@@ -0,0 +1,36 @@
+from typing import List, Union, Any
+
+def flatten_array(arr: Union[List[Any], Any]) -> List[Any]:
+    """
+    Recursively flatten a nested array of arbitrary depth into a single-level list.
+    
+    Args:
+        arr (Union[List[Any], Any]): The input array to be flattened. 
+                                     Can be a nested list or a single element.
+    
+    Returns:
+        List[Any]: A flattened list containing all elements from the input.
+    
+    Examples:
+        >>> flatten_array([1, [2, 3], [4, [5, 6]]])
+        [1, 2, 3, 4, 5, 6]
+        >>> flatten_array([])
+        []
+        >>> flatten_array(1)
+        [1]
+    """
+    # Base case: if input is not a list, return it as a single-element list
+    if not isinstance(arr, list):
+        return [arr]
+    
+    # If list is empty, return empty list
+    if not arr:
+        return []
+    
+    # Recursive flattening
+    flattened = []
+    for item in arr:
+        # Recursively flatten each item and extend the result
+        flattened.extend(flatten_array(item))
+    
+    return flattened
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diff --git a/src/string_reversal.py b/src/string_reversal.py
new file mode 100644
index 00000000..fbefab5b
--- /dev/null
+++ b/src/string_reversal.py
@@ -0,0 +1,23 @@
+def reverse_string(input_string: str) -> str:
+    """
+    Reverse the given input string manually.
+
+    Args:
+        input_string (str): The string to be reversed.
+
+    Returns:
+        str: The reversed string.
+
+    Raises:
+        TypeError: If the input is not a string.
+    """
+    # Check if input is a string
+    if not isinstance(input_string, str):
+        raise TypeError("Input must be a string")
+    
+    # Manual string reversal using list conversion and iteration
+    reversed_chars = []
+    for char in input_string:
+        reversed_chars.insert(0, char)
+    
+    return ''.join(reversed_chars)
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diff --git a/tests/test_array_utils.py b/tests/test_array_utils.py
new file mode 100644
index 00000000..96f268e4
--- /dev/null
+++ b/tests/test_array_utils.py
@@ -0,0 +1,31 @@
+import pytest
+from src.array_utils import flatten_array
+
+def test_flatten_simple_nested_array():
+    """Test flattening a simply nested array."""
+    assert flatten_array([1, [2, 3], 4]) == [1, 2, 3, 4]
+
+def test_flatten_deeply_nested_array():
+    """Test flattening a deeply nested array."""
+    assert flatten_array([1, [2, [3, 4]], [5, [6, 7]]]) == [1, 2, 3, 4, 5, 6, 7]
+
+def test_flatten_empty_array():
+    """Test flattening an empty array."""
+    assert flatten_array([]) == []
+
+def test_flatten_single_element():
+    """Test flattening a single non-list element."""
+    assert flatten_array(5) == [5]
+
+def test_flatten_mixed_types_array():
+    """Test flattening an array with mixed types and nesting."""
+    assert flatten_array([1, 'a', [2, [3.14]], [True, []]]) == [1, 'a', 2, 3.14, True]
+
+def test_flatten_nested_empty_arrays():
+    """Test flattening an array with nested empty arrays."""
+    assert flatten_array([1, [], [2, []], 3]) == [1, 2, 3]
+
+def test_flatten_multiple_level_nesting():
+    """Test flattening an array with multiple levels of nesting."""
+    nested_array = [1, [2, [3, [4, [5]]]], 6]
+    assert flatten_array(nested_array) == [1, 2, 3, 4, 5, 6]
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diff --git a/tests/test_string_reversal.py b/tests/test_string_reversal.py
new file mode 100644
index 00000000..2c1dd4af
--- /dev/null
+++ b/tests/test_string_reversal.py
@@ -0,0 +1,33 @@
+import pytest
+from src.string_reversal import reverse_string
+
+def test_reverse_standard_string():
+    """Test reversing a standard string."""
+    assert reverse_string("hello") == "olleh"
+
+def test_reverse_empty_string():
+    """Test reversing an empty string."""
+    assert reverse_string("") == ""
+
+def test_reverse_palindrome():
+    """Test reversing a palindrome."""
+    assert reverse_string("racecar") == "racecar"
+
+def test_reverse_with_spaces():
+    """Test reversing a string with spaces."""
+    assert reverse_string("hello world") == "dlrow olleh"
+
+def test_reverse_with_special_characters():
+    """Test reversing a string with special characters."""
+    assert reverse_string("a1b2c3!@#") == "#@!3c2b1a"
+
+def test_reverse_unicode_string():
+    """Test reversing a string with unicode characters."""
+    assert reverse_string("こんにちは") == "はちにんこ"
+
+def test_invalid_input_type():
+    """Test that a TypeError is raised for non-string input."""
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(12345)
+        reverse_string(None)
+        reverse_string(["list"])
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