Add comparision with horizontal line via +y - similar to wiggle

Author: yvonnefroehlich

examples/gallery/lines/curves_area.py

@@ -7,7 +7,6 @@
 be drawn.
 To plot an anomaly along a track use :meth:`pygmt.Figure.grdlandmask` and see the
 gallery example :doc:`Wiggle along tracks </gallery/lines/wiggle>`.
-
 """
 
 # %%
@@ -57,4 +56,21 @@
 
 fig.show()
 
+
+# %%
+# Compare to a horizontal line.
+
+# Set up new Figure instance
+fig = gmt.Figure()
+fig.basemap(region=[-10, 10, -5, 5], projection="X15c/5c", frame=True)
+
+fig.plot(
+    data=data_df[["x", "y1"]],
+    fill="p8",
+    pen="1p,black,solid",
+    fill_between="c+gp17+p1p,black,dashed+y0.42",
+)
+
+fig.show()
+
 # sphinx_gallery_thumbnail_number = 1