code: def hello():
      """
      Say hello to user
      """
      _check_call(_LIB.XLearnHello())
  
imports: import sys
  import os
  import ctypes
  from numpy import ndarray
  from .base import Series, DataFrame
  import numpy
  from .base import _LIB, XLearnHandle
  from .base import _check_call, c_str
  from .data import DMatrix
label_desc: Use image node_id 4 for calling a global function with example usage: hello() without return types