code: def _triangles(G, e):
      """Return list of all triangles containing edge e"""
      u, v = e
      if u not in G:
          raise nx.NetworkXError(f"Vertex {u} not in graph")
      if v not in G[u]:
          raise nx.NetworkXError(f"Edge ({u}, {v}) not in graph")
      triangle_list = []
      for x in G[u]:
          if x in G[v]:
              triangle_list.append((u, v, x))
      return triangle_list
  
file_path: networkx/networkx/generators/line.py
imports: from collections import defaultdict
  from functools import partial
  from itertools import combinations
  import networkx
  from networkx.utils import arbitrary_element
  from networkx.utils.decorators import not_implemented_for
label_desc: Use image node_id 5 for calling a global function with example usage: _triangles(G, e) and returns: triangle_list