matplotlib ylabel TypeError: 'str' object is not callable : <p>I have noticed some strange behavior that I can't understand in matplotlib.pyplot  </p>

<p>When I call the ylabel method I get as TypeError as seen below. This does not happen with the xlabel method. The string value there is find and my plot prints.</p>

<p>What have I missed?</p>

<pre><code>TypeError                                 Traceback (most recent call last)
&lt;ipython-input-85-5a3cfeebed52&gt; in &lt;module&gt;()
      4 plt.grid(False)
      5 #plt.ylabel('Relative Search Freq')
----&gt; 6 plt.ylabel('This is the Y Label')
      7 plt.xlabel('This is the X Label')
      8 plt.legend()

TypeError: 'str' object is not callable
</code></pre>

<p>The plot does print but without the ylabel or any of the code after the error which seems normal behavior.</p>
