title: predict statsmodel argument Error
body: <p>I am trying to predict outofsample values for an array. 
  Python code:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  from statsmodels.tsa.arima_model import ARIMA
  
      dates = pd.date_range('2012-07-09','2012-07-30')
      series = [43.,32.,63.,98.,65.,78.,23.,35.,78.,56.,45.,45.,56.,6.,63.,45.,64.,34.,76.,34.,14.,54.]
      res = pd.Series(series, index=dates)
      r = ARIMA(res,(1,2,0))
      pred = r.predict(start='2012-07-31', end='2012-08-31')
  </code></pre>
  
  <p>I am getting this error.I see I have given two argument but compiler return I have given 3. </p>
  
  <pre><code>Traceback (most recent call last):
    File "XXXXXXXXX/testfile.py", line 12, in &lt;module&gt;
      pred = r.predict(start='2012-07-31', end='2012-08-31')
  TypeError: predict() takes at least 2 arguments (3 given)
  </code></pre>
  
  <p>Please help</p>