code: def _available_impls(func: Callable) -> list[tuple[Signature, Any]]:
      """Find all available implementations for a fused cython function."""
      impls = []
      mod = importlib.import_module(func.__module__)
  
      signatures = getattr(func, "__signatures__", None)
      if signatures is not None:
          # Cython function with __signatures__ should be fused and thus
          # indexable
          func_map = cast(Mapping, func)
          candidates = [func_map[key] for key in signatures]
      else:
          candidates = [func]
      for candidate in candidates:
          name = candidate.__name__
          capsule = mod.__pyx_capi__[name]
          llc = LowLevelCallable(capsule)
          try:
              signature = Signature.from_c_types(llc.signature.encode())
          except KeyError:
              continue
          impls.append((signature, capsule))
      return impls
  
imports: import ctypes
  import importlib
  import re
  from collections.abc import Mapping
  from dataclasses import dataclass
  from typing import Any, Callable, Optional, cast
  import numba
  import numpy
  from numpy.typing import DTypeLike
  from scipy import LowLevelCallable
label_desc: Use image node_id 1 for calling a global function with example usage: _available_impls(func) and returns: impls