enh(plot): Edge ops & data fron North-->South

Author: ankostis

graphtik/plot.py

@@ -611,7 +611,7 @@ class Theme:
     ## EDGE
     ##
 
-    kw_edge = {}
+    kw_edge = {"tailport": "s", "headport": "n"}
     kw_edge_optional = {"style": ["dashed"]}
     kw_edge_sideffect = {"color": "blue"}
     #: Added conditionally if `alias_of` found in edge-attrs.

test/test_plot.py

@@ -562,12 +562,12 @@ def test_node_dot_str0(dot_str_pipeline):
                 ><B>FN:</B> test.test_plot.func</TD>
             </TR>
         </TABLE>>, shape=plain, tooltip=<cu:sto:m>];
-        <edge> -> <node>;
-        <edge> -> <cu&#58;sto&#58;m>;
-        <digraph&#58; strict> -> <node>;
-        <digraph&#58; strict> -> <cu&#58;sto&#58;m>;
-        <node> -> <&lt;graph&gt;>;
-        <cu&#58;sto&#58;m> -> <&lt;graph&gt;>;
+        <edge> -> <node>  [headport=n, tailport=s];
+        <edge> -> <cu&#58;sto&#58;m>  [headport=n, tailport=s];
+        <digraph&#58; strict> -> <node>  [headport=n, tailport=s];
+        <digraph&#58; strict> -> <cu&#58;sto&#58;m>  [headport=n, tailport=s];
+        <node> -> <&lt;graph&gt;>  [headport=n, tailport=s];
+        <cu&#58;sto&#58;m> -> <&lt;graph&gt;>  [headport=n, tailport=s];
         legend [URL="https://graphtik.readthedocs.io/en/latest/_images/GraphtikLegend.svg", fillcolor=yellow, shape=component, style=filled, target=_blank];
         }
         """
@@ -607,9 +607,9 @@ def test_node_dot_str1(dot_str_pipeline, monkeypatch):
         </TABLE>>, shape=plain, tooltip=<cu:sto:m>];
         }
 
-        <edge> -> <cu&#58;sto&#58;m>;
-        <digraph&#58; strict> -> <cu&#58;sto&#58;m>;
-        <cu&#58;sto&#58;m> -> <&lt;graph&gt;>;
+        <edge> -> <cu&#58;sto&#58;m>  [headport=n, tailport=s];
+        <digraph&#58; strict> -> <cu&#58;sto&#58;m>  [headport=n, tailport=s];
+        <cu&#58;sto&#58;m> -> <&lt;graph&gt;>  [headport=n, tailport=s];
         legend [URL="https://graphtik.readthedocs.io/en/latest/_images/GraphtikLegend.svg", fillcolor=yellow, shape=component, style=filled, target=_blank];
         }
         """