code: def create_test_graph():
      """
      Creates a simple graph for testing the BreadthFirstWalk class. The node ids are string or integers. Each node
      also has a label based on the type of its id such that nodes with string ids and those with integer ids have
      labels 's' and 'n' respectively.
  
      Returns:
          A simple graph with 13 nodes and 24 edges (including self loops for all but two of the nodes) in
          networkx format.
  
      """
      nodes = {
          "s": pd.DataFrame(
              index=["0", "5", "7", "self loner", "loner"]
          ),
          "n": pd.DataFrame(index=[1, 2, 3, 4, 6, 8, 9, 10]),
      }
      edges = pd.DataFrame(
          [
              ("0", 1),
              ("0", 2),
              (1, 3),
              (1, 4),
              (3, 6),
              (4, "7"),
              (4, 8),
              (2, "5"),
              ("5", 9),
              ("5", 10),
              ("0", "0"),
              (1, 1),
              (3, 3),
              (6, 6),
              (4, 4),
              ("7", "7"),
              (8, 8),
              (2, 2),
              ("5", "5"),
              (9, 9),
              (
                  "self loner",
                  "self loner",
              ),  # node that is not connected with any other nodes but has self loop
          ],
          columns=["source", "target"],
      )
  
      return StellarGraph(nodes, edges)
  
file_path: stellargraph/tests/data/test_metapath_walker.py
imports: import pandas
  import numpy
  import pytest
  from stellargraph.data.explorer import UniformRandomMetaPathWalk
  from stellargraph.core.graph import StellarGraph
  from ..test_utils.graphs import example_graph_random
label_desc: Use image node_id 1 for calling a global function with example usage: create_test_graph() and returns: StellarGraph