code: def _createShapelet(self, coeffs):
          
          n_coeffs = len(coeffs)
          num_n = self._get_num_n(n_coeffs)
          shapelets=np.zeros((num_n+1, num_n+1))
          n = 0
          k = 0
          for coeff in coeffs:
              shapelets[n-k][k] = coeff
              k += 1
              if k == n + 1:
                  n += 1
                  k = 0
          return shapelets
docs: returns a shapelet array out of the coefficients *a, up to order l
  
          :param num_l: order of shapelets
          :type num_l: int.
          :param coeff: shapelet coefficients
          :type coeff: floats
          :returns:  complex array
          :raises: AttributeError, KeyError