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Hi, Welcome back.

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We're going to use the accumulator pattern a lot in this course.

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Previously, you've seen how to accumulate a number,

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a count, or a sum.

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In this lesson, you're going to accumulate lists and strings.

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With lists, you'll start with an empty list and then

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you'll mutate it repeatedly by appending another item each time.

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With strings, similarly, you will start with

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an empty string and extend it repeatedly with

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concatenation and reassignment so that you get a longer and longer string accumulated.

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At the end of this lesson, you should be able to read and write code that

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accumulates lists and strings. See you later!