title: Funny behavior in method of pandas
body: <p>I was working with pandas in my IPython window and I accidentally forgot to add the parentheses after a method call to the pandas groupby object:</p>
  
  <pre><code>In [68]: df_first.groupby('build_number').std
  Out[68]: &lt;bound method DataFrameGroupBy.std of &lt;pandas.core.groupby.DataFrameGroupBy object at 0x7f2742f930d0&gt;&gt;
  </code></pre>
  
  <p>But instead of an error or exception that might tell me that I miss out the parentheses, I get the message in <code>Out[68]</code>. After putting the parentheses, I then get the expected output:</p>
  
  <pre><code>In [69]: df_first.groupby('build_number').std()
  Out[69]: 
                       cycles
  build_number               
  1300          108044.174347
  1301          108041.973597
  1302          108042.702563
  1303          108043.290047
  1304          108043.024902
  1305          108042.704441
  
  In [70]: 
  </code></pre>
  
  <p>So I'm really curious why I did not get an error when I forgot the <code>()</code> earlier. Is this a bug in pandas?</p>
  
  <p>Thank you.</p>