code: def _protected_sqrt(x1):
      """Closure of square root for negative arguments."""
      return np.sqrt(np.abs(x1))
  
file_path: gplearn/gplearn/functions.py
imports: import numpy
  from joblib import wrap_non_picklable_objects
label_desc: Use image node_id 3 for calling a global function with example usage: _protected_sqrt(x1) and returns: np