Updated based on feedback

Altered underlying image to represent three rows of four baskets each, and updated text to follow this change. Used 'veg' as the variable name rather than 'x' (I needed something SHORT to keep the graphic from getting too cluttered, so I opted for 'veg' over 'produce' or 'vegetables'); and made minor text changes to align with suggestions for clarity.

Author: kris-joseph

_episodes/04-lists.md

@@ -161,78 +161,76 @@ does not.
 > Since a list can contain any Python variables, it can even contain other lists.
 >
 > For example, you could represent the products on the shelves of a small grocery shop
-> as a nested list called x:
+> as a nested list called `veg`:
 >
-> [![x is represented as a shelf full of produce. There are four rows of vegetables
-> on the shelf, and each row contains five baskets of vegetables. We can label
+> ![`veg` is represented as a shelf full of produce. There are three rows of vegetables
+> on the shelf, and each row contains three baskets of vegetables. We can label
 > each basket according to the type of vegetable it contains, so the top row
-> contains (from left to right) lettuce, lettuce, peppers, zucchini, squash,
-> and basil.](../fig/04_groceries_x.png)]
+> contains (from left to right) lettuce, lettuce, and peppers.](../fig/04_groceries_veg.png)
 >
 > To store the contents of the shelf in a nested list, you write it this way:
 >
 > ~~~
-> x = [['lettuce', 'lettuce', 'peppers', 'zucchini', 'squash', 'basil'],
->      ['lettuce', 'lettuce', 'peppers', 'zucchini', 'peppers', 'parsley'],
->      ['lettuce', 'cilantro', 'peppers', 'zucchini', 'squash', 'spinach'],
->      ['cabbage', 'broccoli', 'asparagus', 'zucchini', 'squash', 'cauliflower']]
+> veg = [['lettuce', 'lettuce', 'peppers', 'zucchini'],
+>      ['lettuce', 'lettuce', 'peppers', 'zucchini'],
+>      ['lettuce', 'cilantro', 'peppers', 'zucchini']]
 > ~~~
 > {: .language-python}
 >
-> Here are some visual examples of how indexing a list of lists `x` works. First,
-> you can reference each row on the shelf as a separate list. For example, x[2]
-> represents the list of baskets on the third row of the shelf.
+> Here are some visual examples of how indexing a list of lists `veg` works. First,
+> you can reference each row on the shelf as a separate list. For example, `veg[2]`
+> represents the bottom row, which is a list of the baskets in that row.
 >
-> [![x is now shown as a list of four rows, with x[0] representing the top row of
-> five baskets, x[1] representing the second row, x[2] representing the third row,
-> and x[3] representing the bottom row.](../fig/04_groceries_x0.png)]
+> ![`veg` is now shown as a list of three rows, with `veg[0]` representing the top row of
+> three baskets, `veg[1]` representing the second row, and `veg[2]` representing the bottom row.](../fig/04_groceries_veg0.png)
 >
 > Index operations using the image would work like this:
 >
 > ~~~
-> print(x[2])
+> print(veg[2])
 > ~~~
 > {: .language-python}
 >
 > ~~~
-> ['lettuce', 'cilantro', 'peppers', 'zucchini', 'squash', 'spinach']
+> ['lettuce', 'cilantro', 'peppers', 'zucchini']
 > ~~~
 > {: .output}
 >
 > ~~~
-> print(x[0])
+> print(veg[0])
 > ~~~
 > {: .language-python}
 >
 > ~~~
-> ['lettuce', 'lettuce', 'peppers', 'zucchini', 'squash', 'basil']
+> ['lettuce', 'lettuce', 'peppers', 'zucchini']
 > ~~~
 > {: .output}
 >
 > To reference a specific basket on a specific shelf, you use two indexes. The first
 > index represents the row (from top to bottom) and the second index represents
 > the specific basket (from left to right).
-> [![x is now shown as a two-dimensional grid, with each basket labeled according to
+> ![`veg` is now shown as a two-dimensional grid, with each basket labeled according to
 > its index in the nested list. The first index is the row number and the second
-> index is the basket number, so x[1][4] represents the basket on the far right
-> side of the second row (basket 4 on row 1): parsley](../fig/04_groceries_x00.png)]
+> index is the basket number, so `veg[1][3]` represents the basket on the far right
+> side of the second row (basket 4 on row 2): zucchini](../fig/04_groceries_veg00.png)
 >
 > ~~~
-> print(x[0][0])
+> print(veg[0][0])
 > ~~~
 > {: .language-python}
 >
 > ~~~
 > 'lettuce'
 > ~~~
+> {: .output}
 >
 > ~~~
-> print(x[3][2])
+> print(veg[1][2])
 > ~~~
 > {: .language-python}
 >
 > ~~~
-> 'asparagus'
+> 'peppers'
 > ~~~
 > {: .output}
 >