adding some examples to AttributesRO reference

.gitignore

@@ -1 +1,3 @@
-/build
+/build
+/.idea
+/freeplane_docs.iml

src/docs/scripting/Reference.md

@@ -1,9 +1,17 @@
 # Scripting Reference (work in progress)
 
+To test the example codes you can use the Freeplane's script editor:
+- select the test node
+- open the script editor ( **Menu->Tools->Edit script…** )
+- create a new script ( **Actions->New script** )
+- paste the example code in the editor
+- test the code ( **Actions->Run** )
+- if you want, you can select other nodes and repeat the test
+
 ```groovy
 {{#include reference.groovy}}
 ```
 
 <footer id="open-on-gh">
 Want to contribute? <a href="https://github.com/freeplane/docs/edit/main/src/docs/scripting/reference.groovy">Edit the groovy file on github.</a>
-</footer>
+</footer>

src/docs/scripting/reference.groovy

@@ -4,44 +4,136 @@
   AttributesRO
 */
 
-// Returns "true", if the selected node contains an attribute key that is equal to "aaa". Returns "false", otherwise.
+/*
+For the following code examples you can paste the following branch in Freeplane.
+Select and copy the following lines and paste as a branch from the selected node in your mind map.
+
+Sample Branch 01
+	item A: Attributes
+		item A1
+		+	myAttribute	my text value
+		+	aaa	v_aaa
+		item A2
+		+	otherAttribute	aaa
+		item A3
+		item A4
+		+	aaa	first
+		+	bbb	second
+		+	aaa	third
+		+	aaa	fourth
+	item B
+	item C
+
+ */
 
+// Returns "true", if the selected node contains an attribute key that is equal to "aaa". Returns "false", otherwise.
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns true
+        node "item A2" returns false
+        node "item A3" returns false
+        node "item A4" returns true
+ */
 node.attributes.containsKey("aaa")
 
 // Returns the index of the first attribute with the name "aaa" if one exists or -1 otherwise.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns 1 (it's the second attribute)
+        node "item A2" returns -1
+        node "item A3" returns -1
+        node "item A4" returns 0 (the first one is in the first attribute's position)
+ */
 node.attributes.findFirst("aaa")
 
 // Returns the attribute value at the index 1.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns 'v_aaa'
+        node "item A2" returns exception: "org.freeplane.plugin.script.ExecuteScriptException: Array index out of range: 1, Array index out of range: 1"
+        node "item A3" returns exception: "org.freeplane.plugin.script.ExecuteScriptException: Array index out of range: 1, Array index out of range: 1"
+        node "item A4" returns 'second'
+ */
 node.attributes.get(1)
 
 //  Returns the values of all the attributes that has the key equal to "aaa".
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns [v_aaa]
+        node "item A2" returns []
+        node "item A3" returns []
+        node "item A4" returns [first, third, fourth]
+ */
 node.attributes.getAll("aaa")
 
 // Returns the first value of an attribute with the name "aaa" or null otherwise.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns v_aaa
+        node "item A2" returns null
+        node "item A3" returns null
+        node "item A4" returns first
+ */
 node.attributes.getFirst("aaa")
 
 // Returns the attribute key at the index 1.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns aaa
+        node "item A2" returns exception: "org.freeplane.plugin.script.ExecuteScriptException: Array index out of range: 1, Array index out of range: 1"
+        node "item A3" returns exception: "org.freeplane.plugin.script.ExecuteScriptException: Array index out of range: 1, Array index out of range: 1"
+        node "item A4" returns bbb
+ */
 node.attributes.getKey(1)
 
 // Returns all attributes as a map.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns {myAttribute=my text value, aaa=v_aaa}
+        node "item A2" returns {otherAttribute=aaa}
+        node "item A3" returns {}
+        node "item A4" returns {aaa=fourth, bbb=second}  // (note that it takes for aaa the value of the last attribute)
+ */
 node.attributes.map
 
 // Returns all attribute names in the proper sequence.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns [myAttribute, aaa]
+        node "item A2" returns [otherAttribute]
+        node "item A3" returns []
+        node "item A4" returns [aaa, bbb, aaa, aaa]
+ */
 node.attributes.names
 
 // Returns "true", if the selected node has no attributes. Returns "false", otherwise.
-
-node.attributes.empty
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns false
+        node "item A2" returns false
+        node "item A3" returns true
+        node "item A4" returns false
+*/
+ node.attributes.empty
 
 // Returns the number of attributes.
-
+/*
+    using "Sample Branch 01":
+    selecting
+        node "item A1" returns 2
+        node "item A2" returns 1
+        node "item A3" returns 0
+        node "item A4" returns 4
+*/
 node.attributes.size()
 
 /*