title: To run a python function with multiple parameters
body: <p>I have a function here:</p>
  
  <pre><code>def ROC(dfH, n):  
      M = dfH['Close'].diff(n - 1)  
      N = dfH['Close'].shift(n - 1)  
      ROC = pd.Series(M / N, name = 'ROC_' + str(n))  
      dfH = dfH.join(ROC)  
      return dfH
  </code></pre>
  
  <p>With the above function I want to make multiple columns by changing the value of n so i run the code</p>
  
  <pre><code>a = (4, 8)
  for j in a:
      ROC(dfH, n=a)
  </code></pre>
  
  <p>which gets to be wrong. please help
  thanks in advance.</p>
  
  <p>`</p>