diff --git a/src/array_flattener.py b/src/array_flattener.py
new file mode 100644
index 00000000..f103f0e1
--- /dev/null
+++ b/src/array_flattener.py
@@ -0,0 +1,44 @@
+from typing import List, Union, Any, Iterable, Tuple
+
+def flatten_array(arr: Union[List[Any], Tuple[Any, ...]]) -> List[Any]:
+    """
+    Flatten a nested array (list or tuple) to a single-level list.
+    
+    This function recursively flattens a nested list or tuple of arbitrary depth 
+    into a single-level list. It handles nested lists, tuples, and other 
+    iterable types while preserving non-iterable elements.
+    
+    Args:
+        arr (Union[List[Any], Tuple[Any, ...]]): The input nested list/tuple to be flattened.
+    
+    Returns:
+        List[Any]: A flattened list containing all non-list/non-tuple elements.
+    
+    Raises:
+        TypeError: If the input is not a list or tuple.
+    
+    Examples:
+        >>> flatten_array([1, [2, 3], [4, [5, 6]]])
+        [1, 2, 3, 4, 5, 6]
+        >>> flatten_array([1, 2, 3])
+        [1, 2, 3]
+        >>> flatten_array([])
+        []
+    """
+    # Check if input is a valid iterable
+    if not isinstance(arr, (list, tuple)):
+        raise TypeError("Input must be a list or tuple")
+    
+    # Initialize result list
+    flattened = []
+    
+    # Iterate through each element
+    for item in arr:
+        # If item is a list or tuple, recursively flatten
+        if isinstance(item, (list, tuple)):
+            flattened.extend(flatten_array(item))
+        else:
+            # Add non-list/non-tuple items directly
+            flattened.append(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..14ac38e0
--- /dev/null
+++ b/src/string_reversal.py
@@ -0,0 +1,33 @@
+def reverse_string(s: str) -> str:
+    """
+    Reverse the given string manually, preserving all original characters.
+
+    Args:
+        s (str): The input string to be reversed.
+
+    Returns:
+        str: The reversed string.
+
+    Raises:
+        TypeError: If the input is not a string.
+    """
+    # Validate input is a string
+    if not isinstance(s, str):
+        raise TypeError("Input must be a string")
+    
+    # Manual string reversal using a list and two-pointer technique
+    # Convert string to list to allow manipulation
+    chars = list(s)
+    
+    # Two-pointer approach to swap characters
+    left, right = 0, len(chars) - 1
+    while left < right:
+        # Swap characters
+        chars[left], chars[right] = chars[right], chars[left]
+        
+        # Move pointers
+        left += 1
+        right -= 1
+    
+    # Convert back to string and return
+    return ''.join(chars)
\ No newline at end of file
diff --git a/tests/test_array_flattener.py b/tests/test_array_flattener.py
new file mode 100644
index 00000000..fbbf55de
--- /dev/null
+++ b/tests/test_array_flattener.py
@@ -0,0 +1,33 @@
+import pytest
+from src.array_flattener import flatten_array
+
+def test_flatten_simple_list():
+    """Test flattening a simple list"""
+    assert flatten_array([1, 2, 3]) == [1, 2, 3]
+
+def test_flatten_nested_list():
+    """Test flattening a nested list"""
+    assert flatten_array([1, [2, 3], [4, [5, 6]]]) == [1, 2, 3, 4, 5, 6]
+
+def test_flatten_empty_list():
+    """Test flattening an empty list"""
+    assert flatten_array([]) == []
+
+def test_flatten_deeply_nested_list():
+    """Test flattening a deeply nested list"""
+    assert flatten_array([1, [2, [3, [4]]], 5]) == [1, 2, 3, 4, 5]
+
+def test_flatten_mixed_types():
+    """Test flattening a list with mixed types"""
+    assert flatten_array([1, 'a', [2, 'b'], [3, [4, 'c']]]) == [1, 'a', 2, 'b', 3, 4, 'c']
+
+def test_flatten_tuple_nested():
+    """Test flattening a list with tuple nesting"""
+    assert flatten_array([1, (2, 3), [4, (5, 6)]]) == [1, 2, 3, 4, 5, 6]
+
+def test_invalid_input_type():
+    """Test that TypeError is raised for non-list input"""
+    with pytest.raises(TypeError, match="Input must be a list"):
+        flatten_array("not a list")
+    with pytest.raises(TypeError, match="Input must be a list"):
+        flatten_array(123)
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diff --git a/tests/test_string_reversal.py b/tests/test_string_reversal.py
new file mode 100644
index 00000000..94834877
--- /dev/null
+++ b/tests/test_string_reversal.py
@@ -0,0 +1,38 @@
+import pytest
+from src.string_reversal import reverse_string
+
+def test_reverse_string_basic():
+    """Test basic string reversal."""
+    assert reverse_string("hello") == "olleh"
+    assert reverse_string("python") == "nohtyp"
+
+def test_reverse_string_empty():
+    """Test reversing an empty string."""
+    assert reverse_string("") == ""
+
+def test_reverse_string_single_char():
+    """Test reversing a single character string."""
+    assert reverse_string("a") == "a"
+
+def test_reverse_string_with_spaces():
+    """Test reversing a string with spaces."""
+    assert reverse_string("hello world") == "dlrow olleh"
+
+def test_reverse_string_with_special_chars():
+    """Test reversing a string with special characters and mixed content."""
+    assert reverse_string("a1b2c3!@#") == "#@!3c2b1a"
+
+def test_reverse_string_with_unicode():
+    """Test reversing a string with unicode characters."""
+    assert reverse_string("café") == "éfac"
+
+def test_reverse_string_invalid_input():
+    """Test that TypeError is raised for non-string inputs."""
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(123)
+    
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(None)
+    
+    with pytest.raises(TypeError, match="Input must be a string"):
+        reverse_string(["hello"])
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