title: Filling null vals in a dataframe
body: <p>I Have a column like this</p>
  <p>Jacob</p>
  <p>NaN</p>
  <p>NaN</p>
  <p>Max</p>
  <p>NaN</p>
  <p>Prince</p>
  <p>NaN</p>
  <p>NaN</p>
  <p>NaN</p>
  <p>I want to fill NaN vals like this</p>
  <p>Jacob</p>
  <p>Jacob</p>
  <p>Jacob</p>
  <p>Max</p>
  <p>Max</p>
  <p>Prince</p>
  <p>Prince</p>
  <p>Prince</p>
  <p>Prince</p>
  <p>Help Please</p>