code: def _park(z1, z2, x1, x2, x3, x4):
      """Internal park function."""
      x1 = max(1e-4, x1)
      ret1 = (
          (x1 / 2)
          * (np.sqrt(1 + (x2 + x3**2) * x4 / (x1**2)) - 1)
          * z1
      )
      ret2 = (x1 + 3.2 * x4) * np.exp(1 + np.sin(x3)) * z2
      return ret1 + ret2
  
file_path: dragonfly/examples/synthetic/syn_cnn_2/syn_cnn_2.py
imports: import numpy
  from dragonfly.nn.syn_nn_functions import syn_func1_common
  from synthetic.park2_4.park2_4 import sub_park_1, sub_park_2, sub_park_3, sub_park_4
label_desc: Use image node_id 2 for calling a global function with example usage: _park(z1, z2, x1, x2, x3, x4) and returns: unknown