code: def _linear_jac(t, y, a):
      """Jacobian of a * y is a."""
      return a
  
file_path: scipy/scipy/integrate/tests/test_banded_ode_solvers.py
imports: import itertools
  import numpy
  from numpy.testing import assert_allclose
  from scipy.integrate import ode
label_desc: Use image node_id 3 for calling a global function with example usage: _linear_jac(t, y, a) and returns: a