Intro

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Reading Items from a List

~7 mincode completion

A list holds an ordered sequence of values:

scores = [90, 85, 77, 100]

You reach an item by its index, and indices start at 0, not 1:

scores[0]     # 90     the first item
scores[1]     # 85     the second item
scores[-1]    # 100    the last item
scores[-2]    # 77     the second to last
len(scores)   # 4      how many items

Negative indices count backwards from the end. scores[-1] is much better than scores[len(scores) - 1], and it is what Python programmers actually write.

Asking for an index that does not exist raises IndexError. With 4 items the valid indices are 0, 1, 2 and 3, so scores[4] fails.

Your task:

Write first_and_last(values) that returns a tuple of the first item and the last item.

For [3, 9, 4, 7] it returns (3, 7). Assume the list has at least one item.

Example Tests

Picks the ends out of a four-item list

Input: {"values":[3,9,4,7]}

Expected: [3,7]

With two items, first and last are the two items

Input: {"values":[10,20]}

Expected: [10,20]

With one item, it is both the first and the last

Input: {"values":[42]}

Expected: [42,42]

Python

def first_and_last(values):
    """
    Return the first and last items of a list.

    Args:
        values: a non-empty list

    Returns:
        A tuple (first_item, last_item).
    """
    # YOUR CODE HERE
    pass

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