title: Flag a row if column values present in another dataframe
body: <p>I have the following two dataframes.</p>
  <p>df1:</p>
  <pre><code>     name  age   
  0   Alice   12   
  1     Bob   32         
  2   Chuck    9            
  3   Daren   76             
  4    Eddy   21  
  </code></pre>
  <p>and df2:</p>
  <pre><code>     name  age  hair_color 
  0   Alice   12       brown 
  1     Bob   32      blonde  
  2    Cory   36       brown     
  3   David    3       white       
  4    Eddy   21      orange
  </code></pre>
  <p>I want to extend df1 to include a column 'match', such that whenever the ['name', 'age'] matches in df2, it will include a <code>1</code> in the column, otherwise a <code>0</code>. My goal is to have the resulting dataframe:</p>
  <pre><code>     name  age  match 
  0   Alice   12      1
  1     Bob   32      1  
  2   Chuck    9      0     
  3   Daren   76      0      
  4    Eddy   21      1
  </code></pre>
  <p>Any tips for best approaches? Thanks!</p>