def first_item(a):
    """
    Return the first item of an iterable.

    Parameters
    ----------
    a : object
        Iterable to get the first item from.

    Returns
    -------
    object

    Raises
    ------
    StopIteration
        If the iterable is empty.

    Examples
    --------
    >>> a = range(10)
    >>> first_item(a)
    0
    """
    return next(iter(a))
