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Find nth Bell Number

The Bell numbers are a sequence of numbers that represent the number of ways to partition a set of `n` elements. The sequence starts with `1` for `n = 0`, and subsequent numbers can be calculated using a triangular array known as the Bell triangle.

Write a Python function `bell_number(n)` that computes the nth Bell number. The function should take an integer `n` as input and return the nth Bell number.

#### Example Usage
```python [main.nopy]
print(bell_number(0))  # Output: 1
print(bell_number(1))  # Output: 1
print(bell_number(2))  # Output: 2
print(bell_number(3))  # Output: 5
print(bell_number(4))  # Output: 15
```

#### Constraints
- The input `n` will be a non-negative integer.
- The function should handle inputs up to at least `n = 10` efficiently.
def bell_number(n):
    """
    Calculate the nth Bell number.

    Args:
        n (int): The index of the Bell number to compute.

    Returns:
        int: The nth Bell number.
    """
    # Initialize the Bell triangle or other data structure
    # Implement the logic to compute the nth Bell number
    pass