code: def _calc_essl_blue(ratio):
      """Calculate values for blue based on scaled and clipped ratio."""
      blue_a = 0.75 - 1.5 * ratio
      blue_b = 0.25 - (ratio - 0.75) ** 2
      blue = xr.where(blue_a > blue_b, blue_a, blue_b)
      blue.data = da.clip(blue.data, 0, 1)
      return blue
  
file_path: satpy/satpy/enhancements/atmosphere.py
imports: import datetime
  import dask.array
  import xarray
label_desc: Use image node_id 5 for calling a global function with example usage: _calc_essl_blue(ratio) and returns: blue