code: def generate_graph(idtype, grad=False, add_data=True):
      g = dgl.graph([]).to(F.ctx(), dtype=idtype)
      g.add_nodes(10)
      u, v = [], []
      # create a graph where 0 is the source and 9 is the sink
      for i in range(1, 9):
          u.append(0)
          v.append(i)
          u.append(i)
          v.append(9)
      # add a back flow from 9 to 0
      u.append(9)
      v.append(0)
      g.add_edges(u, v)
      if add_data:
          ncol = F.randn((10, D))
          ecol = F.randn((17, D))
          if grad:
              ncol = F.attach_grad(ncol)
              ecol = F.attach_grad(ecol)
          g.ndata["h"] = ncol
          g.edata["l"] = ecol
      return g
  
imports: import unittest
  import backend
  import dgl
  from utils import parametrize_idtype
label_desc: Use image node_id 1 for calling a global function with example usage: generate_graph(idtype, grad, add_data) and returns: g