code: def gen_by_mutation():
      g = dgl.graph([])
      src, dst = edge_pair_input()
      g.add_nodes(10)
      g.add_edges(src, dst)
      return g
  
imports: import math
  import numbers
  import backend
  import dgl
  import networkx
  import numpy
  import pytest
  import scipy.sparse
  from dgl import DGLError
label_desc: Use image node_id 6 for calling a global function with example usage: gen_by_mutation() and returns: g