class_docstr: A simple interface to Natural Earth shapefiles.
  
  See https://www.naturalearthdata.com/
code: def _validate_scale(self):
      if self.scale not in ("110m", "50m", "10m"):
          raise ValueError(
              f"{self.scale!r} is not a valid Natural Earth scale. "
              'Valid scales are "110m", "50m", and "10m".'
          )
  
imports: from abc import ABCMeta, abstractmethod
  import numpy
  import shapely.geometry
  import cartopy.crs
  import cartopy.io.shapereader
label_desc: Use image node_id 3 for calling the NaturalEarthFeature obj's underlying member method code with example usage: obj._validate_scale() without return types