title: Merge rows in a dataframe where the rows are disjoint and contain NAs
body: <p>I have a dataframe that has two rows:</p>
  
  <pre><code>| code | name  | v1 | v2 | v3 | v4 |
  |------|-------|----|----|----|----|
  | 345  | Yemen | NA | 2  | 3  | NA |
  | 346  | Yemen | 4  | NA | NA | 5  |
  </code></pre>
  
  <p>Is there an easy way to merge these two rows?
  What if I rename "345" in "346", would that make things easier?</p>