Remove spurious private method and fix a comment

Author: alihamdan

doc/usage/Plotting.md

@@ -50,15 +50,18 @@ To visualize the voltage profile of a network, use one of the `plot_<backend>` m
 ... ).plot_plotly().show()
 ```
 
-<!-- en = rlf.ElectricalNetwork.from_catalogue("LVFeeder36360", "Winter")
+<!-- # To generate the following iframe, run:
+import roseau.load_flow as rlf
+en = rlf.ElectricalNetwork.from_catalogue("LVFeeder36360", "Winter")
 en.solve_load_flow()
 (
   rlf.plotting.voltage_profile(en, mode="min", traverse_transformers=True, distance_unit="m")
   .plot_plotly()
   .write_html(
-      "doc/_static/Plotting/Voltage_Profile_LVFeeder36360_Plotly2.html", include_plotlyjs="cdn"
+      "doc/_static/Plotting/Voltage_Profile_LVFeeder36360_Plotly.html", include_plotlyjs="cdn"
   )
-) -->
+)
+-->
 
 <iframe src="../_static/Plotting/Voltage_Profile_LVFeeder36360_Plotly.html" height="500px" width="100%" frameborder="0"></iframe>
 

roseau/load_flow/plotting.py

@@ -1007,7 +1007,7 @@ def _from_network(
             raise ValueError(f"Bus {starting_bus_id!r} not found in the network.")
 
         try:
-            distance_factor = cls._get_distance_factor(distance_unit)
+            distance_factor = Q_(1.0, units="km").m_as(distance_unit)
         except PintError as e:
             raise ValueError(f"Invalid distance unit: {distance_unit}") from e
 
@@ -1149,10 +1149,6 @@ def _ylabel(self) -> str:
             label = f"{self.mode.capitalize()} {label}"
         return label
 
-    @staticmethod
-    def _get_distance_factor(distance_unit: str) -> float:
-        return Q_(1.0, units="km").m_as(distance_unit)
-
     def _edge_segs(self, edge: "VoltageProfileEdge") -> tuple[tuple[float, float], tuple[float, float]]:
         """Get the segments for an edge in the form ((x1, y1), (x2, y2))."""
         return (