def roll_d20():
    """
    Simulate the roll of a 20-sided die (d20).

    This function generates a random integer between 1 and 20, inclusive,
    which represents the outcome of a single roll of a d20.

    Returns:
        str: The result of the die roll.
    """
    import random

    dice_role_outcome = random.randint(1, 20)
    output_string = f"You rolled a {dice_role_outcome}"
    return output_string