code: def ref_hard_sigmoid(x):
      return np.maximum(0, np.minimum(1, x * 0.2 + 0.5))
  
file_path: nnabla/python/test/function/test_hard_sigmoid.py
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 1 for calling a global function with example usage: ref_hard_sigmoid(x) and returns: np