diff --git a/mapytex/calculus/core/__init__.py b/mapytex/calculus/core/__init__.py
index 47ae35f..dd1c797 100644
--- a/mapytex/calculus/core/__init__.py
+++ b/mapytex/calculus/core/__init__.py
@@ -6,10 +6,33 @@
 #
 # Distributed under terms of the MIT license.
 
-"""
+r"""
 Abstracts tools for calculs manipulations
+
+:example:
+
+>>> t = Tree.from_str("2+3*4")
+>>> print(t)
++
+ > 2
+ > *
+ | > 3
+ | > 4
+>>> print(t.apply_on_last_level(compute))
++
+ > 2
+ > 12
+>>> tree2txt(t)
+'2 + 3 * 4'
+>>> tree2tex(t)
+'2 + 3 \\times 4'
+
 """
 
+from .tree import Tree
+from .compute import compute
+from .renders import tree2txt, tree2tex
+
 
 # -----------------------------
 # Reglages pour 'vim'