class_docstr: Generic GDAL transformer base class
  
  Notes
  -----
  Subclasses must have a _transformer attribute and implement a `_transform` method.
code: def _transform(self, xs, ys, zs, transform_direction):
      raise NotImplementedError
  
imports: from contextlib import ExitStack
  from functools import partial
  import math
  import numpy
  import warnings
  from affine import Affine
  from rasterio.env import env_ctx_if_needed
  from rasterio._transform import _transform_from_gcps, RPCTransformerBase, GCPTransformerBase
  from rasterio.enums import TransformDirection, TransformMethod
  from rasterio.control import GroundControlPoint
  from rasterio.rpc import RPC
  from rasterio.errors import TransformError, RasterioDeprecationWarning
label_desc: Use image node_id 7 for calling the TransformerBase obj's underlying member method code with example usage: obj._transform(xs, ys, zs, transform_direction) without return types