title: Inserting a tuple into an empty pandas dataframe
body: <p>I would like to insert a row into an empty DataFrame. However, this seems to fail for a DataFrame with predefined indices and when the elements include a tuple or list prompting the error:</p>
  
  <blockquote>
    <p>ValueError: setting an array element with a sequence.</p>
  </blockquote>
  
  <p>The example code is as follows:</p>
  
  <pre><code>df = pd.DataFrame(columns=['idx1', 'idx2', 'col1', 'col2', 'col3'])
  df.set_index(['idx1', 'idx2'], inplace=True)
  df.loc[(1,2),:] = [3,4,(5,6)]
  print(df)
  </code></pre>