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This is a small detail, but usually you put a colon when a sentence announces an example, as for the second example :
The second form here is the rightward assignment we’ve already seen. This can be used in
more complex patterns:
[1, "potato", 2, "potato"] => [first, String, second, String]
There is a point instead of a colon for the second example
with that name.
and third example
This pattern assigns first but not second.
I was wondering if it was a previous pattern. In this case it would be particularly relevant to put a colon because This pattern announces the next example :
[1, "potato", 2, "potato"] in [Integer => first, Integer, Integer => second, String]