code: def edgelist_to_adjacency(edgelist):
      
      adjacency = dict()
      for u, v in edgelist:
          if u in adjacency:
              adjacency[u].add(v)
          else:
              adjacency[u] = {v}
          if v in adjacency:
              adjacency[v].add(u)
          else:
              adjacency[v] = {u}
      return adjacency
docs: Converts an iterator of edges to an adjacency dict.
  
      Args:
          edgelist (iterable):
              An iterator over 2-tuples where each 2-tuple is an edge.
  
      Returns:
          dict: The adjacency dict. A dict of the form {v: Nv, ...} where v is a node in a graph and
          Nv is the neighbors of v as an set.