code: def single_source_dijkstra(
      G, source, target=None, cutoff=None, weight="weight"
  ):
      """Find shortest weighted paths and lengths from a source node.
  
      Compute the shortest path length between source and all other
      reachable nodes for a weighted graph.
  
      Uses Dijkstra's algorithm to compute shortest paths and lengths
      between a source and all other reachable nodes in a weighted graph.
  
      Parameters
      ----------
      G : NetworkX graph
  
      source : node label
          Starting node for path
  
      target : node label, optional
          Ending node for path
  
      cutoff : integer or float, optional
          Length (sum of edge weights) at which the search is stopped.
          If cutoff is provided, only return paths with summed weight <= cutoff.
  
  
      weight : string or function
          If this is a string, then edge weights will be accessed via the
          edge attribute with this key (that is, the weight of the edge
          joining `u` to `v` will be ``G.edges[u, v][weight]``). If no
          such edge attribute exists, the weight of the edge is assumed to
          be one.
  
          If this is a function, the weight of an edge is the value
          returned by the function. The function must accept exactly three
          positional arguments: the two endpoints of an edge and the
          dictionary of edge attributes for that edge. The function must
          return a number or None to indicate a hidden edge.
  
      Returns
      -------
      distance, path : pair of dictionaries, or numeric and list.
          If target is None, paths and lengths to all nodes are computed.
          The return value is a tuple of two dictionaries keyed by target nodes.
          The first dictionary stores distance to each target node.
          The second stores the path to each target node.
          If target is not None, returns a tuple (distance, path), where
          distance is the distance from source to target and path is a list
          representing the path from source to target.
  
      Raises
      ------
      NodeNotFound
          If `source` is not in `G`.
  
      Examples
      --------
      >>> G = nx.path_graph(5)
      >>> length, path = nx.single_source_dijkstra(G, 0)
      >>> length[4]
      4
      >>> for node in [0, 1, 2, 3, 4]:
      ...     print(f"{node}: {length[node]}")
      0: 0
      1: 1
      2: 2
      3: 3
      4: 4
      >>> path[4]
      [0, 1, 2, 3, 4]
      >>> length, path = nx.single_source_dijkstra(G, 0, 1)
      >>> length
      1
      >>> path
      [0, 1]
  
      Notes
      -----
      Edge weight attributes must be numerical.
      Distances are calculated as sums of weighted edges traversed.
  
      The weight function can be used to hide edges by returning None.
      So ``weight = lambda u, v, d: 1 if d['color']=="red" else None``
      will find the shortest red path.
  
      Based on the Python cookbook recipe (119466) at
      https://code.activestate.com/recipes/119466/
  
      This algorithm is not guaranteed to work if edge weights
      are negative or are floating point numbers
      (overflows and roundoff errors can cause problems).
  
      See Also
      --------
      single_source_dijkstra_path
      single_source_dijkstra_path_length
      single_source_bellman_ford
      """
      return multi_source_dijkstra(
          G, {source}, cutoff=cutoff, target=target, weight=weight
      )
  
imports: from collections import deque
  from heapq import heappop, heappush
  from itertools import count
  import networkx
  from networkx.algorithms.shortest_paths.generic import _build_paths_from_predecessors
label_desc: Use image node_id 6 for calling a global function with example usage: single_source_dijkstra(G, source, target, cutoff, weight) and returns: multi_source_dijkstra