title: Returning an Array Using Recursion in Python 3
body: <p>I currently have this code:</p>
  
  <pre><code>import numpy as np
  
  def mapfeature_binominal_array(x1,x2,n=6,list=[]):
  
      if len(list)==0:
          list.append(x1)
          list.append(x2)
  
      if n==1:
          print(np.array(list))
          return np.array(list)
      else:
          for i in range(0,n+1):
              formula=((x1)**(n-i))*((x2)**(i))
              list.append(formula)
  
  
          mapfeature_binominal_array(x1,x2,n-1,list)
  
  test_array=mapfeature_binominal_array(-0.25,1.5)
  </code></pre>
  
  <p>which prints out the following output:</p>
  
  <pre><code>[ -2.50000000e-01   1.50000000e+00   2.44140625e-04  -1.46484375e-03
     8.78906250e-03  -5.27343750e-02   3.16406250e-01  -1.89843750e+00
     1.13906250e+01  -9.76562500e-04   5.85937500e-03  -3.51562500e-02
     2.10937500e-01  -1.26562500e+00   7.59375000e+00   3.90625000e-03
    -2.34375000e-02   1.40625000e-01  -8.43750000e-01   5.06250000e+00
    -1.56250000e-02   9.37500000e-02  -5.62500000e-01   3.37500000e+00
     6.25000000e-02  -3.75000000e-01   2.25000000e+00]
  </code></pre>
  
  <p>However, when i try:</p>
  
  <pre><code>print(test_array)
  </code></pre>
  
  <p>I get <code>None</code>.</p>
  
  <p>I am wondering why it does not assign the array to <code>test_array</code>.</p>