FormField.kt

// ...

fun Collection<FormField<*>>.clearError() {
    forEach { formField -> formField.clearError() }
}

fun Collection<FormField<*>>.clearFocus() {
    forEach { formField -> formField.clearFocus() }
}

fun Collection<FormField<*>>.disable() {
    forEach { formField -> formField.disable() }
}

fun Collection<FormField<*>>.enable() {
    forEach { formField -> formField.enable() }
}