code: def _isolve(
      _isolve_solve,
      A,
      b,
      x0=None,
      *,
      tol=1e-5,
      atol=0.0,
      maxiter=None,
      M=None,
      check_symmetric=False,
  ):
      if x0 is None:
          x0 = tree_map(jnp.zeros_like, b)
  
      b, x0 = device_put((b, x0))
  
      if maxiter is None:
          size = sum(bi.size for bi in tree_leaves(b))
          maxiter = 10 * size  # copied from scipy
  
      if M is None:
          M = _identity
      A = _normalize_matvec(A)
      M = _normalize_matvec(M)
  
      if tree_structure(x0) != tree_structure(b):
          raise ValueError(
              "x0 and b must have matching tree structure: "
              f"{tree_structure(x0)} vs {tree_structure(b)}"
          )
  
      if _shapes(x0) != _shapes(b):
          raise ValueError(
              "arrays in x0 and b must have matching shapes: "
              f"{_shapes(x0)} vs {_shapes(b)}"
          )
  
      isolve_solve = partial(
          _isolve_solve, x0=x0, tol=tol, atol=atol, maxiter=maxiter, M=M
      )
  
      # real-valued positive-definite linear operators are symmetric
      def real_valued(x):
          return not issubclass(x.dtype.type, np.complexfloating)
  
      symmetric = (
          all(map(real_valued, tree_leaves(b)))
          if check_symmetric
          else False
      )
      x = lax.custom_linear_solve(
          A,
          b,
          solve=isolve_solve,
          transpose_solve=isolve_solve,
          symmetric=symmetric,
      )
      info = None
      return x, info
  
imports: from functools import partial
  import operator
  import numpy
  import jax
  import jax.numpy
  from jax import device_put
  from jax import lax
  from jax import scipy
  from jax.tree_util import tree_leaves, tree_map, tree_structure, tree_reduce, Partial
  from jax._src import dtypes
  from jax._src.lax import lax
  from jax._src.util import safe_map
label_desc: Use image node_id 12 for calling a global function with example usage: _isolve(_isolve_solve, A, b, x0) and returns: x,  info, unknown