some missing code on vegeta2102 blog trying to add it back in

VeryString.kt

private val charList = listOf<Char>('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
        'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z')
val isValidCharacters: (Char) -> Boolean = {c -> charList.contains(Character.toLowerCase(c))}
val isCharNumberUnderScore: (String) -> Boolean = { s: String -> 
   val allValid = s.all { ch ->
         isValidCharacters(ch) || Character.valueOf(ch).isDigit() || Character.valueOf(ch) == '_'
   }
   allValid
}
class Validator {
    fun verify(shoeName: String): Boolean {
         return isCharNumberUnderScore(shoeName)
    }
}

@lupajz I recently checked your blog on medium Two-way data binding with InputTextEditText Google Material

strange compilation error on line 13

aah, the solution was to make every static, AKA in kotlin speak into a companion object used the declared class