title: Intersection of two or more DataFrame columns
body: <p>I am trying to find the intersect of three dataframes, however the <code>pd.intersect1d</code> does not like to use three dataframes. </p>
  
  <pre><code>import numpy as np
  import pandas as pd
  df1 = pd.DataFrame(np.random.randint(0,10,size=(10, 4)), columns=list('ABCD'))
  df2 = pd.DataFrame(np.random.randint(0,10,size=(10, 4)), columns=list('BCDE'))
  df3 = pd.DataFrame(np.random.randint(0,10,size=(10, 4)), columns=list('CDEF'))
  
  inclusive_list = np.intersect1d(df1.columns, df2.columns, df3.columns)
  </code></pre>
  
  <p>Error: </p>
  
  <pre><code>ValueError: The truth value of a Index is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
  </code></pre>
  
  <p>The <code>inclusive_list</code> should only include column names C &amp; D. Any help would be appreciated. Thank you. </p>