1 files changed, 18 insertions, 12 deletions
diff --git a/rdflib/extras/external_graph_libs.py b/rdflib/extras/external_graph_libs.py
index 11d2ca1e..f50994b5 100644
--- a/rdflib/extras/external_graph_libs.py
+++ b/rdflib/extras/external_graph_libs.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 # encoding: utf-8
+from __future__ import annotations
 
 """Convert (to and) from rdflib graphs to other well known graph libraries.
 
@@ -13,6 +14,10 @@ see ../../test/test_extras_external_graph_libs.py for conditional tests
 """
 
 import logging
+from typing import TYPE_CHECKING, Any, Dict, List
+
+if TYPE_CHECKING:
+    from rdflib.graph import Graph
 
 logger = logging.getLogger(__name__)
 
@@ -22,9 +27,9 @@ def _identity(x):
 
 
 def _rdflib_to_networkx_graph(
-    graph,
+    graph: Graph,
     nxgraph,
-    calc_weights,
+    calc_weights: bool,
     edge_attrs,
     transform_s=_identity,
     transform_o=_identity,
@@ -70,7 +75,7 @@ def _rdflib_to_networkx_graph(
 
 
 def rdflib_to_networkx_multidigraph(
-    graph, edge_attrs=lambda s, p, o: {"key": p}, **kwds
+    graph: Graph, edge_attrs=lambda s, p, o: {"key": p}, **kwds
 ):
     """Converts the given graph into a networkx.MultiDiGraph.
 
@@ -124,8 +129,8 @@ def rdflib_to_networkx_multidigraph(
 
 
 def rdflib_to_networkx_digraph(
-    graph,
-    calc_weights=True,
+    graph: Graph,
+    calc_weights: bool = True,
     edge_attrs=lambda s, p, o: {"triples": [(s, p, o)]},
     **kwds,
 ):
@@ -187,8 +192,8 @@ def rdflib_to_networkx_digraph(
 
 
 def rdflib_to_networkx_graph(
-    graph,
-    calc_weights=True,
+    graph: Graph,
+    calc_weights: bool = True,
     edge_attrs=lambda s, p, o: {"triples": [(s, p, o)]},
     **kwds,
 ):
@@ -250,9 +255,9 @@ def rdflib_to_networkx_graph(
 
 
 def rdflib_to_graphtool(
-    graph,
-    v_prop_names=[str("term")],
-    e_prop_names=[str("term")],
+    graph: Graph,
+    v_prop_names: List[str] = [str("term")],
+    e_prop_names: List[str] = [str("term")],
     transform_s=lambda s, p, o: {str("term"): s},
     transform_p=lambda s, p, o: {str("term"): p},
     transform_o=lambda s, p, o: {str("term"): o},
@@ -313,7 +318,8 @@ def rdflib_to_graphtool(
     True
 
     """
-    import graph_tool as gt
+    # pytype error: Can't find module 'graph_tool'.
+    import graph_tool as gt  # pytype: disable=import-error
 
     g = gt.Graph()
 
@@ -323,7 +329,7 @@ def rdflib_to_graphtool(
     eprops = [(epn, g.new_edge_property("object")) for epn in e_prop_names]
     for epn, eprop in eprops:
         g.edge_properties[epn] = eprop
-    node_to_vertex = {}
+    node_to_vertex: Dict[Any, Any] = {}
     for s, p, o in graph:
         sv = node_to_vertex.get(s)
         if sv is None: