code: def area(group):
      return group.drop_duplicates("g_id").area.sum()
  
file_path: deepgraph/doc/source/tutorials/precipitation.py
imports: import os
  import xarray
  import matplotlib.pyplot
  import numpy
  import pandas
  import deepgraph
  from mpl_toolkits.basemap import Basemap
  from scipy.cluster.hierarchy import linkage, fcluster
label_desc: Use image node_id 5 for calling a global function with example usage: area(group) and returns: group