minor #3628 Rename variables used in map method (alexander-schranz)

This PR was submitted for the 3.x branch but it was merged into the 2.x branch instead.

Discussion
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Rename variables used in map method

As most people (including me) are lazy people to read text and mostly looks just at the code. Using `key` and `value` as variable make the map faster to understand which argument is which one :)

Commits
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b74cf2a Rename variables used in map method

Author: fabpot

doc/filters/map.rst

@@ -27,7 +27,7 @@ The arrow function also receives the key as a second argument:
         "Alice": "Dupond",
     } %}
 
-    {{ people|map((last, first) => "#{first} #{last}")|join(', ') }}
+    {{ people|map((value, key) => "#{value} #{key}")|join(', ') }}
     {# outputs Bob Smith, Alice Dupond #}
 
 Note that the arrow function has access to the current context.