title: ValueError: Series.replace cannot use dict-value and non-None to_replace
body: <p>Code:</p>
  <pre><code>h1=df[df[&quot;native-country&quot;]!=&quot;?&quot;]
  f1=h1.mode()
  df['native-country'] = df['native-country'].replace(&quot;?&quot;,df['native-country'].mode())
  </code></pre>
  <p>Error:</p>
  <pre><code>ValueError: Series.replace cannot use dict-value and non-None to_replace
  </code></pre>
  <p>I dont know why im getting this error hope someone could help me</p>