title: How to use alt.condition() in alt.color(condition=)?
body: <p>I'm new to altair so i want to be able to see my code more clearly. that's why i'm trying to use long version coding. my problem is that, i could't find any documentation on how to use a <code>alt.color(condition=)</code> . How can i use <code>condition=</code> preferably with <code>alt.condition()</code>?</p>
  <pre><code>brush = alt.selection_interval()
  
  alt.Chart(cars).mark_point().encode(
      alt.Y(&quot;Horsepower&quot;),
      alt.X(&quot;Miles_per_Gallon&quot;, title=&quot;consumption&quot;),
      #alt.Tooltip([&quot;Name&quot;, &quot;Origin&quot;]),
      #color=alt.condition(brush, 'Origin:N', alt.value('White')) I Know with this line my code will work 
      alt.Color(condition= alt.condition(brush,
                     alt.Color('Origin:N', legend=None),
                     alt.value('lightgray')))
  ).add_selection(
      brush
  )
  </code></pre>