title: Fill missing data in a linear model
body: <p>I have the following <code>val list = listOf(1, 2, 3, null, null, 6, 7)</code> I'd like to fill the null value for the following result: <code>listOf(1, 2, 3, 4, 5, 6, 7)</code></p>
  <p>I couldn't find any method doing this in Kotlin, do you guys have an idea?</p>
  <p>EDIT: I'm adding more details, the list will always have a beginning element and an ending element (ie no list as <code>listOf(null, 2 ,3)</code> or <code>listOf(1, 2, null)</code>) I preprocess this.</p>
  <p>In my example I gave Integer element but it could be Float or Double</p>