def conditional_items(conditional_steps):
    """Adds items to a list if a condition is fulfilled.

    Parameters
    ----------
    conditional_steps: tuple (item, condition, [alternative])
        A tuple with an item, a boolean condition, and an optional alternative item that will be added instead if the 
        condition does not hold
    Returns
    -------
    The list of items (or alternatives) that fulfill the conditions
    """
    result = []
    for conditional_step in conditional_steps:
        if len(conditional_step) == 3:
            step, condition, alternative = conditional_step
            if condition:
                result.append(step)
            else:
                result.append(alternative)
        else:
            step, condition = conditional_step
            if condition:
                result.append(step)
    return result
