code: def _normalize_interpolate_how(how):
      if callable(how):
          return how
      elif how in _interpolate_lookup:
          return _interpolate_lookup[how]
      raise ValueError("Unknown interpolation method: {0}".format(how))
  
imports: from __future__ import annotations
  from collections.abc import Iterator
  from io import BytesIO
  import warnings
  import numpy
  import numba
  import toolz
  import xarray
  import dask.array
  from PIL.Image import fromarray
  from datashader.colors import rgb, Sets1to3
  from datashader.utils import nansum_missing, ngjit
label_desc: Use image node_id 3 for calling a global function with example usage: _normalize_interpolate_how(how) and returns: how, _interpolate_lookup