title: Firestore not-equal (!=) count as range filter
body: <p>I'm trying to use the not-equal (!=) operator in a query that already has a range filter (geohash query), thinking this should behave the same as an equal (==) query.</p>
  <p>But upon running that query, I get prompted with this error message:</p>
  <blockquote>
  <p>Unhandled Exception: The initial orderBy() field &quot;[[FieldPath([location, geohash]), false]][0][0]&quot; has to be the same as the where() field parameter &quot;FieldPath([expire_at])&quot; when an inequality operator is invoked.</p>
  </blockquote>
  <p>Now, I understand that, due to how indexes works, firestore only allow ONE range filter per query. What I don't understand is why the <code>not-equal</code> operation here is considered a range filter.</p>
  <p>In other words: Is the <code>not-equal</code> operation just synthetic sugar for <code>.where(x &gt; y).where(x &lt; y)</code> ?</p>