def add(vec1, vec2):
    """Adds two vectors.

    Adds a length-n list to another length-n list.

    Args:
        vec1 (list): First vector.
        vec2 (list): Second vector.

    Returns:
        Sum of vec1 and vec2.
    """
    assert len(vec1) == len(vec2)
    return [vec1[i] + vec2[i] for i in range(len(vec1))]