Merge pull request #98 from Bernardoow/save2file

Added example about save2file

docs/source/examples.rst

@@ -136,6 +136,14 @@ the data field is appended into JSON string. For example,
     >>> print(tree.to_json(with_data=True))
     {"Harry": {"data": null, "children": [{"Bill": {"data": null}}, {"Jane": {"data": null, "children": [{"Diane": {"data": null}}, {"Mark": {"data": null}}]}}, {"Mary": {"data": null}}]}}
 
+**Example 10**: Save tree into file
+  The function save2file require a filename.
+  The file is opened to write using mode 'ab'.
+
+.. code-block:: sh
+
+    >>> tree.save2file('tree.txt')
+
 
 Advanced Usage
 ----------------

examples/save_tree_2_file.py

@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+
+from treelib import Tree
+
+tree = Tree()
+tree.create_node("Harry", "harry")  # root node
+tree.create_node("Jane", "jane", parent="harry")
+tree.create_node("Bill", "bill", parent="harry")
+tree.create_node("Diane", "diane", parent="jane")
+tree.create_node("Mary", "mary", parent="diane")
+tree.create_node("Mark", "mark", parent="jane")
+tree.save2file('tree.txt')