code: def sigmoid(x):
      """Sigmoid function"""
      return 1.0 / (1.0 + np.exp(-x))
  
file_path: cornac/cornac/utils/common.py
imports: import numbers
  import numpy
  import scipy.sparse
  from .fast_sparse_funcs import inplace_csr_row_normalize_l1, inplace_csr_row_normalize_l2
label_desc: Use image node_id 1 for calling a global function with example usage: sigmoid(x) and returns: unknown