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diff --git a/scripts/fibonacci.py b/scripts/fibonacci.py
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+"""
+This module provides a function to calculate the nth Fibonacci number using an iterative approach.
+"""
+
+def fibonacci(n: int) -> int:
+    """
+    Calculate the nth Fibonacci number.
+
+    The Fibonacci sequence is a series of numbers where each number is the sum of the two preceding ones.
+    Typically starting with 0 and 1.
+
+    Args:
+        n (int): The position in the Fibonacci sequence to calculate. Must be a non-negative integer.
+
+    Returns:
+        int: The nth Fibonacci number.
+
+    Raises:
+        ValueError: If n is not a non-negative integer.
+    """
+    if not isinstance(n, int):
+        raise ValueError("Input must be an integer.")
+    if n < 0:
+        raise ValueError("Input must be a non-negative integer.")
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+
+    a, b = 0, 1
+    for _ in range(2, n + 1):
+        a, b = b, a + b
+    return b
+
+if __name__ == "__main__":
+    # Example usage:
+    try:
+        position = 10
+        result = fibonacci(position)
+        print(f"The {position}th Fibonacci number is: {result}")
+    except ValueError as e:
+        print(f"Error: {e}")