def k_shell(G, k=None, core_number=None):
 def k_filter(v, k, c):
  return (c[v] == k)
 return _core_subgraph(G, k_filter, k, core_number)

def k_shell ( G , k = None , core_number = None ) : def k_filter ( v , k , c ) : return ( c [ v ] == k ) return _core_subgraph ( G , k_filter , k , core_number )
return the k-shell of g .