title: TypeError: Mean() missing 1 required positional argument: 'data'
body: <p>I'm trying to program a basic mean calculator using classes. However, I'm getting the error</p>
  <pre><code>TypeError: Mean() missing 1 required positional argument: 'data'
  </code></pre>
  <p>I have two files: one which contains the class with the mean function and then one which calls it, and that is when I'm getting the error. My code is:</p>
  <pre><code>class Statistics:
      def __init__(self,mean_x,mean_y,var,covar):
          self.mean_x=mean_x
          self.mean_y=mean_y
          self.var=var
          self.covar=covar
      
      def Mean(self,data):
          return sum(data)/float(len(data))
  </code></pre>
  <p>And the code which throws the error is:</p>
  <pre><code>from Statistics import Statistics 
  X=(0,1,3,5)
  mean_x=Statistics.Mean(X)
  print(mean_x)
  </code></pre>