code: def _get_cameras(self, **kwargs):
      cameras = kwargs.get("cameras", self.cameras)
      if cameras is None:
          msg = "Cameras must be specified either at initialization \
                  or in the forward pass of the shader."
          raise ValueError(msg)
  
      return cameras
  
imports: import warnings
  from typing import Optional
  import torch
  import torch.nn
  from ...common.datatypes import Device
  from ...structures.meshes import Meshes
  from ..blending import BlendParams, hard_rgb_blend, sigmoid_alpha_blend, softmax_rgb_blend
  from ..lighting import PointLights
  from ..materials import Materials
  from ..splatter_blend import SplatterBlender
  from ..utils import TensorProperties
  from .rasterizer import Fragments
  from .shading import _phong_shading_with_pixels, flat_shading, gouraud_shading, phong_shading
label_desc: Use image node_id 2 for calling the ShaderBase obj's underlying member method code with example usage: obj._get_cameras() and returns: cameras