code: def ref_softplus(x, beta):
      return (np.log(np.exp(x * beta, dtype=x.dtype) + 1)) / beta
  
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_softplus(x, beta) and returns: unknown