code: def saturate(src, dst):
      sr, sg, sb, sa = extract_scaled(src)
      dr, dg, db, da = extract_scaled(dst)
  
      a = min(1, sa + da)
      if a == 0:
          return np.uint32(0)
      factor = min(sa, 1 - da)
      r = (factor * sr + dr * da) / a
      g = (factor * sg + dg * da) / a
      b = (factor * sb + db * da) / a
      return combine_scaled(r, g, b, a)
  
file_path: datashader/datashader/composite.py
imports: from __future__ import annotations
  import numba
  import numpy
  import os
label_desc: Use image node_id 8 for calling a global function with example usage: saturate(src, dst) and returns: combine_scaled, np