Confusing naming of function passed to Array.map

Hello,
not a real issue but just a naming of a method that confused me for a bit.
In [datasource/launch](https://github.com/apollographql/fullstack-tutorial/blob/master/final/server/src/datasources/launch.js#L10) there is method called `launchReducer` passed to `Array.map`. This method is responsible to take each launch returned by the Rest API and **mapping** it to another object.
So I guess this function should be called `lauchMapper`, because that's what it does. It doesn't reduce multiple element into a single one, isn't it?

Just highlighting this because it is a bit confusing

打开 final/server/src/datasources/launch.js 中 launchReducer 的定义，并检查它传递给 Array.map 的位置。检查对该函数的任何其他引用，然后一致地更新命名，使函数名称能够反映其映射作用。

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