build.gradle how to apply a closure from another file

I have a closure of defined in a another build.gradle file called other.gradle. Here is the contents:

Closure callback =  {

    productFlavors {  
        ...
        devel {
            ...
        }

        prod {
            ...
        }
    }
}

Now in my build.gradle file I want to call this closure like this:

apply from: 'other.gradle'
productFlavors(callback());

but I keep getting an error that callback() cant be found. Both files are in the same directory. My issue is how do i get the build.gradle file to see the callback closure in the 'other.gradle' file.