title: Pandas np.where or np.select generate multiple columns in 1 line code
body: <p>I have a df:</p>
  <pre><code>contract    RB  BeginDate   ValIssueDate    EndDate Valindex0
  1   A00118  46  19000100    19880901    19841231    50
  2   A00118  46  19850100    19880901    99999999    50
  3   A00118  47  19000100    19880901    19831231    47
  4   A00118  47  19840100    19880901    19841299    47
  </code></pre>
  <p>I need to add new columns based on conditions:</p>
  <pre><code>condition = True
  
  df['Valindex0']=np.where(condtion,df['Valindex0'],None)
  df['RB']=np.where(condtion,df['RB'],None)
  </code></pre>
  <p>is there anyway I can do it by 1 line like this:</p>
  <pre><code>conditions=[True,True]
  
  df[['Valindex0','RB']]=np.select[conditions,[df['Valindex0'],df['RB']],default=None]
  </code></pre>
  <p>or</p>
  <pre><code>df['Valindex0'],df['RB']=np.select[conditions,[df['Valindex0'],df['RB']],default=None]
  </code></pre>