MergerLiveData use case for medium article

medium_MergerLiveDataUseCase.kt

/* 
 * before
 */
class ViewModel {
    val nameInput = MutableLiveData("")
    val ageInput = MutableLiveData(0)
}

<layout>
    <data>
        <variable
            name="viewModel"
            type="ViewModel" />
        
        <import type="android.text.TextUtils" />
    </data> 

    <ViewGroup .. >
         ..
         <Button
            ..
            android:enabled="@{!TextUtils.isEmpty(viewModel.nameInput) &amp;&amp; viewModel.ageInput >= 18}"
            />

    </ViewGroup>
</layout>

/* 
 * after
 */
class ViewModel {
    val nameInput = MutableLiveData("")
    val ageInput = MutableLiveData(0)

    val isButtonEnabled =
        MergerLiveData.Two(
            firstSource = nameInput,
            secondSource = ageInput
        ) { name, age ->
            name.isNotEmpty() && age >= 18
        }
}

<layout>
    <data>
        <variable
            name="viewModel"
            type="ViewModel" />
    </data> 

    <ViewGroup .. >
         ..
          <Button
            ..
            android:enabled="@{viewModel.isButtonEnabled}"
            />

    </ViewGroup>
</layout>