title: @cuda.jit(device=True) returns 'DeviceFunctionTemplate' object is not callable
body: <p>I'm working on math method and to reduce execution time I use numba decorator</p>
  <pre class="lang-py prettyprint-override"><code>@numba.jit(nopython=True, nogil=True, cache=True) 
  def analize_tick(data:np.array, index:int, result_signal:np.array) -&gt; None:
     ##I perform an action here and then return result  
     result_sirnal[0]=1
     
  </code></pre>
  <p>it works OK, but when I changed the decorator from <code>@numba.jit(nopython=True, nogil=True, cache=True) </code> to <code>@cuda.jit(device=True)</code> I got the error: <em>'DeviceFunctionTemplate' object is not callable</em>
  Could you advice me how to fix this issue?
  BTW the method recieves three arguments:</p>
  <ul>
  <li>numpy 2 dimensional float array</li>
  <li>int index</li>
  <li>numpy 1 dimensional int array where I return result</li>
  </ul>
  <hr />
  <p><em>UPDATED to add code sample:</em></p>
  <pre class="lang-py prettyprint-override"><code>import unittest
  
  import pandas as pd
  import numpy as np
  import numba
  from numba import cuda
  
  
  @numba.jit(nopython=True, nogil=True, cache=True) 
  # @cuda.jit(device=True)
  def calculate(data:np.array, index:int, options:np.array, result_signal:np.array) -&gt; None:        
      i = data[0]
      b = data[1]
      result_signal[0]= i+b
  
  @numba.jit(nopython=True, nogil=True, cache=True) 
  # @cuda.jit(device=True)
  def for_each(data:np.array,options:np.array, result:np.array) -&gt; None:            
      for index, r in enumerate(data):        
          calculate(r, index, options, result)
          # print(result[0])
  
  class cuda_test(unittest.TestCase):
  
      def test_numba_call(self):
          df = pd.DataFrame([[1, 1], [2, 2]], columns=['c0', 'c1'])
          data = df.to_numpy()
          result = np.array([0], dtype=float)
          options = np.array([0], dtype=float)
          for sigma in range(0, 10, 1):
              options[0] = sigma
              for_each(data, options, result)
  </code></pre>