code: def line_graph() -> StellarGraph:
      nodes = node_features()
      edges = pd.DataFrame(
          [(i, i + 1) for i in range(9)], columns=["source", "target"]
      )
      return StellarGraph(nodes, edges)
  
imports: from stellargraph import StellarGraph, StellarDiGraph, IndexedArray
  import networkx
  import pandas
  import numpy
  import random
  import pytest
label_desc: Use image node_id 13 for calling a global function with example usage: line_graph() and returns: StellarGraph