code: def import_cartopy():
      
      cartopy = None
      has_cartopy = True
      try:
          import cartopy
          WARNINGS['has_cartopy'] = True
      except ImportError:
          has_cartopy = False
          if not WARNINGS['cartopy']:
              print('-W- cartopy is not installed')
              print('    If you want to make maps, install using conda:')
              print('    conda install cartopy')
      WARNINGS['cartopy'] = True
      return has_cartopy, cartopy
docs: Try to import cartopy and print out a help message
      if it is not installed
  
      Returns
      ---------
      has_cartopy : bool
      cartopy : cartopy package if available else None