I have a problem while iterating over array of different types. Let's imagine we have a function that accepts array and key whitch say what type of array it is

function Do(feeds: IGType[] | FBType[], channel: 'IG' | 'FB') 

So when I want to iterate over feeds by Bluebird.map typescript say that

Argument of type 'IGType[] | FBType[]' is not assignable to parameter of 
type 'IterableCollection<IGType>'.
  Type 'FBType[]' is not assignable to type 'IterableCollection<IGType>'.
    Type 'FBType[]' is not assignable to type 'IGType[]'.
      Type 'FBType' is not assignable to type 'IGType'.
        Type 'FBType' is missing the following properties from type 'IGType': cached, meta, $getAllSubdocs, $ignore, and 50 more.ts(2345)