code: def _linear_func(t, y, a):
      """Linear system dy/dt = a * y"""
      return a.dot(y)
  
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 2 for calling a global function with example usage: _linear_func(t, y, a) and returns: a