Proof of concept– combining *begin and *end processor methods

[frewsxcv]

Just sharing in case it's something we want to consider

diff --git a/geozero/src/feature_processor.rs b/geozero/src/feature_processor.rs
index 2b8554a..6b4c8d2 100644
--- a/geozero/src/feature_processor.rs
+++ b/geozero/src/feature_processor.rs
@@ -4,7 +4,7 @@ use crate::property_processor::PropertyProcessor;
 
 /// Feature processing trait
 #[allow(unused_variables)]
-pub trait FeatureProcessor: GeomProcessor + PropertyProcessor {
+pub trait FeatureProcessor: GeomProcessor + PropertyProcessor + Sized {
     /// Begin of dataset processing
     fn dataset_begin(&mut self, name: Option<&str>) -> Result<()> {
         Ok(())
@@ -22,10 +22,16 @@ pub trait FeatureProcessor: GeomProcessor + PropertyProcessor {
         Ok(())
     }
     /// Begin of feature property processing
+    fn write_properties(&mut self, inner: impl FnOnce(&mut Self) -> Result<()>) -> Result<()> {
+        Ok(())
+    }
+    /// Begin of feature property processing
+    #[deprecated]
     fn properties_begin(&mut self) -> Result<()> {
         Ok(())
     }
     /// End of feature property processing
+    #[deprecated]
     fn properties_end(&mut self) -> Result<()> {
         Ok(())
     }
diff --git a/geozero/src/geojson/geojson_reader.rs b/geozero/src/geojson/geojson_reader.rs
index 9d107a4..29fc714 100644
--- a/geozero/src/geojson/geojson_reader.rs
+++ b/geozero/src/geojson/geojson_reader.rs
@@ -121,9 +121,9 @@ fn process_geojson_feature<P: FeatureProcessor>(
     if feature.geometry.is_some() || feature.properties.is_some() {
         processor.feature_begin(idx as u64)?;
         if let Some(ref properties) = feature.properties {
-            processor.properties_begin()?;
-            process_properties(properties, processor)?;
-            processor.properties_end()?;
+            processor.write_properties(|processor| {
+                process_properties(properties, processor)
+            })?;
         }
         if let Some(ref geometry) = feature.geometry {
             processor.geometry_begin()?;
diff --git a/geozero/src/geojson/geojson_writer.rs b/geozero/src/geojson/geojson_writer.rs
index ac7f371..97214b4 100644
--- a/geozero/src/geojson/geojson_writer.rs
+++ b/geozero/src/geojson/geojson_writer.rs
@@ -54,6 +54,12 @@ impl<W: Write> FeatureProcessor for GeoJsonWriter<'_, W> {
         self.out.write_all(b"}")?;
         Ok(())
     }
+    fn write_properties(&mut self, inner: impl FnOnce(&mut Self) -> Result<()>) -> Result<()> {
+        self.out.write_all(br#", "properties": {"#)?;
+        inner(self)?;
+        self.out.write_all(b"}")?;
+        Ok(())
+    }
     fn properties_begin(&mut self) -> Result<()> {
         self.out.write_all(br#", "properties": {"#)?;
         Ok(())