code: def _spread_mixed_term(term):
      # Turns non-diagonal element into a tuple of 4 elements representing 4
      # diagonal points.
      return term, -term, -term, term
  
file_path: tf-quant-finance/tf_quant_finance/math/pde/steppers/douglas_adi_scheme_test.py
imports: import numpy
  import tensorflow.compat.v2
  import tf_quant_finance
  from tensorflow.python.framework import test_util
label_desc: Use image node_id 3 for calling a global function with example usage: _spread_mixed_term(term) and returns: term,  unknown,  unknown,  term