title: AttributeError: 'str' object has no attribute 'dispersion_plot' NLTK
body: <p>I am trying to create a dispersion_plot using NLTK. As far as I can tell, I am following the directions. When I run their example calling the example text that comes with NLTK it works. When I call my own text file, it has the above error. </p>
  
  <p>mine:</p>
  
  <pre><code>&gt;&gt;&gt; text11 = "Text_test.txt"
  &gt;&gt;&gt; text11.dispersion_plot(["semiosis", "dialectic", "essentially", "icon", "logo"])
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: 'str' object has no attribute 'dispersion_plot'
  </code></pre>
  
  <p>Their example code:</p>
  
  <pre><code>text4.dispersion_plot(["citizens", "democracy", "freedom", "duties", "America"])
  </code></pre>
  
  <p>Thankful for any advice/help! </p>