diff --git a/mapytex/calculus/API/expression.py b/mapytex/calculus/API/expression.py
index 3cfec23..8588fde 100644
--- a/mapytex/calculus/API/expression.py
+++ b/mapytex/calculus/API/expression.py
@@ -12,13 +12,13 @@ Expression
 """
 from functools import partial
 from ..core import AssocialTree, Tree, compute, typing, TypingError
-from ..core.random import (
-    extract_rdleaf,
-    extract_rv,
-    random_generator,
-    compute_leafs,
-    replace_rdleaf,
-)
+#from ..core.random import (
+#    extract_rdleaf,
+#    extract_rv,
+#    random_generator,
+#    compute_leafs,
+#    replace_rdleaf,
+#)
 from ..core.MO import moify
 from .tokens import factory
 from .renders import render
diff --git a/mapytex/calculus/API/tokens/number.py b/mapytex/calculus/API/tokens/number.py
index 7e0abb9..9181e27 100644
--- a/mapytex/calculus/API/tokens/number.py
+++ b/mapytex/calculus/API/tokens/number.py
@@ -13,7 +13,7 @@ Tokens representing interger and decimal
 from decimal import Decimal as _Decimal
 from .token import Token
 from ...core.arithmetic import gcd
-from ...core.random.int_gene import filter_random
+#from ...core.random.int_gene import filter_random
 from ...core.MO import MO, MOnumber
 from ...core.MO.fraction import MOFraction
 from random import random
diff --git a/mapytex/calculus/__init__.py b/mapytex/calculus/__init__.py
index 2566253..73d409f 100644
--- a/mapytex/calculus/__init__.py
+++ b/mapytex/calculus/__init__.py
@@ -31,7 +31,7 @@ Expression is the classe wich handle all calculus. It can randomly generate or i
 """
 
 from .API import Expression, Integer, Decimal, render, Polynomial, Fraction
-from .core import random_list
+#from .core import random_list
 from decimal import getcontext
 #getcontext().prec = 2
 
diff --git a/mapytex/calculus/core/__init__.py b/mapytex/calculus/core/__init__.py
index 41e8ad4..1e8d6c5 100644
--- a/mapytex/calculus/core/__init__.py
+++ b/mapytex/calculus/core/__init__.py
@@ -66,7 +66,6 @@ from .tree import Tree, AssocialTree
 from .compute import compute
 from .typing import typing, TypingError
 from .renders import tree2txt, tree2tex
-from .random import list_generator as random_list
 
 
 # -----------------------------
diff --git a/mapytex/calculus/core/str2.py b/mapytex/calculus/core/str2.py
index e0f6d23..edeace7 100644
--- a/mapytex/calculus/core/str2.py
+++ b/mapytex/calculus/core/str2.py
@@ -15,7 +15,6 @@ from decimal import Decimal, InvalidOperation
 from .coroutine import *
 from .operator import is_operator
 from .MO import moify_cor
-from .random.leaf import look_for_rdleaf, RdLeaf
 
 __all__ = ["str2"]
 
@@ -810,38 +809,7 @@ def str2(sink, convert_to_mo=True):
 
     return pipeline
 
-
-def rdstr2(sink):
-    """ Return a pipeline which parse random expression and with sink as endpoint
-
-    :example:
-    >>> rdstr2list = rdstr2(list_sink)
-    >>> rdstr2list("{a}+{a*b}-2")
-    [<RdLeaf a>, '+', <RdLeaf a*b>, '+', <MOnumber -2>]
-    >>> rdstr2list("{a}({b}x+{c})")
-    [<RdLeaf a>, '*', [<RdLeaf b>, '*', <MOstr x>, '+', <RdLeaf c>]]
-    """
-    lfop = lookfor(is_operator)
-    operator_corout = partial(concurent_broadcast, lookfors=[lfop])
-
-    def pipeline(expression):
-        str2_corout = look_for_rdleaf(
-            lookforNumbers(operator_corout(
-                missing_times(moify_cor(pparser(sink)))))
-        )
-
-        for i in expression.replace(" ", ""):
-            str2_corout.send(i)
-        a = str2_corout.throw(STOOOP)
-
-        return a
-
-    return pipeline
-
-
 str2nestedlist = str2(list_sink)
-
-
 # -----------------------------
 # Reglages pour 'vim'
 # vim:set autoindent expandtab tabstop=4 shiftwidth=4:
diff --git a/mapytex/calculus/core/tree.py b/mapytex/calculus/core/tree.py
index 090cab0..d1d379d 100644
--- a/mapytex/calculus/core/tree.py
+++ b/mapytex/calculus/core/tree.py
@@ -11,7 +11,7 @@ Tree class
 
 from .tree_tools import to_nested_parenthesis, postfix_concatenate, show_tree
 from .coroutine import coroutine, STOOOP
-from .str2 import str2, rdstr2
+from .str2 import str2
 from .operator import OPERATORS, is_operator
 
 __all__ = ["Tree", "MutableTree"]
@@ -51,7 +51,7 @@ class Tree:
         self.right_value = right_value
 
     @classmethod
-    def from_str(cls, expression, convert_to_mo=True, random=False):
+    def from_str(cls, expression, convert_to_mo=True):
         """ Initiate a tree from an string expression
 
         :example:
@@ -77,26 +77,8 @@ class Tree:
          > *
          | > 3
          | > n
-        >>> t = Tree.from_str("2+{n}x", random=True)
-        >>> print(t)
-        +
-         > 2
-         > *
-         | > {n}
-         | > x
-        >>> t = Tree.from_str("{a}({b}x+{c})", random=True)
-        >>> print(t)
-        *
-         > {a}
-         > +
-         | > *
-         | | > {b}
-         | | > x
-         | > {c}
-
-
         """
-        t = MutableTree.from_str(expression, convert_to_mo, random)
+        t = MutableTree.from_str(expression, convert_to_mo)
         return cls.from_any_tree(t)
 
     @classmethod
@@ -907,7 +889,7 @@ class MutableTree(Tree):
         self.right_value = right_value
 
     @classmethod
-    def from_str(cls, expression, convert_to_mo=True, random=False):
+    def from_str(cls, expression, convert_to_mo=True):
         """ Initiate the MutableTree
 
         :example:
@@ -963,29 +945,9 @@ class MutableTree(Tree):
          | | > 8
          | | > 3
          | > x
-        >>> t = MutableTree.from_str("{b}*x+{c}", random=True)
-        >>> print(t)
-        +
-         > *
-         | > {b}
-         | > x
-         > {c}
-        >>> t = MutableTree.from_str("{a}*({b}*x+{c})", random=True)
-        >>> print(t)
-        *
-         > {a}
-         > +
-         | > *
-         | | > {b}
-         | | > x
-         | > {c}
         """
-        if random:
-            str_2_mut_tree = rdstr2(cls.sink)
-            return str_2_mut_tree(expression)
-        else:
-            str_2_mut_tree = str2(cls.sink, convert_to_mo)
-            return str_2_mut_tree(expression)
+        str_2_mut_tree = str2(cls.sink, convert_to_mo)
+        return str_2_mut_tree(expression)
 
     @classmethod
     @coroutine
diff --git a/mapytex/calculus/random/__init__.py b/mapytex/calculus/random/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/mapytex/calculus/core/random/__init__.py b/mapytex/calculus/random/core/__init__.py
similarity index 97%
rename from mapytex/calculus/core/random/__init__.py
rename to mapytex/calculus/random/core/__init__.py
index da8f50f..9fe4275 100644
--- a/mapytex/calculus/core/random/__init__.py
+++ b/mapytex/calculus/random/core/__init__.py
@@ -37,7 +37,8 @@ Tree with RdLeaf replaced by generated values
 
 :example:
 
->>> from ..tree import Tree
+>>> from ...core.tree import Tree
+>>> from .leaf import RdLeaf
 >>> rd_t = Tree("/", RdLeaf("a"), RdLeaf("a*k"))
 >>> print(rd_t)
 /
@@ -74,16 +75,16 @@ This function ignores tree structure and works with lists
 __all__ = ["list_generator"]
 
 from random import choice
-from functools import reduce
-from .leaf import RdLeaf
 
 
 def extract_rdleaf(tree):
     """ Extract rdLeaf in a Tree
 
     :example:
-    >>> from ..tree import Tree
+    >>> from ...core.tree import Tree
+    >>> from .leaf import RdLeaf
     >>> rd_t = Tree("+", RdLeaf("a"), RdLeaf("a*k"))
+    >>> from .leaf import RdLeaf
     >>> extract_rdleaf(rd_t)
     ['a', 'a*k']
     >>> rd_t = Tree("+", RdLeaf("a"), 2)
@@ -139,7 +140,8 @@ def compute_leafs(leafs, generated_values):
 def replace_rdleaf(tree, computed_leafs):
     """ Replace RdLeaf by the corresponding computed value
 
-    >>> from ..tree import Tree
+    >>> from ...core.tree import Tree
+    >>> from .leaf import RdLeaf
     >>> rd_t = Tree("+", RdLeaf("a"), RdLeaf("a*k"))
     >>> computed_leafs = {'a': 2, 'a*k': 6}
     >>> print(replace_rdleaf(rd_t, computed_leafs))
diff --git a/mapytex/calculus/core/random/int_gene.py b/mapytex/calculus/random/core/int_gene.py
similarity index 100%
rename from mapytex/calculus/core/random/int_gene.py
rename to mapytex/calculus/random/core/int_gene.py
diff --git a/mapytex/calculus/core/random/leaf.py b/mapytex/calculus/random/core/leaf.py
similarity index 94%
rename from mapytex/calculus/core/random/leaf.py
rename to mapytex/calculus/random/core/leaf.py
index 471ed4b..7be0e65 100644
--- a/mapytex/calculus/core/random/leaf.py
+++ b/mapytex/calculus/random/core/leaf.py
@@ -9,7 +9,7 @@
 """
 
 """
-from ..coroutine import *
+from ...core.coroutine import coroutine, STOOOP
 
 
 @coroutine
@@ -17,7 +17,7 @@ def look_for_rdleaf(target):
     """ Coroutine which look to "{...}" which are RdLeaf
 
     :example:
-    >>> from ..str2 import list_sink
+    >>> from ...core.str2 import list_sink
     >>> str2list = look_for_rdleaf(list_sink)
     >>> for i in "{a}+{a*b}-2":
     ...    str2list.send(i)
diff --git a/mapytex/calculus/random/core/str2.py b/mapytex/calculus/random/core/str2.py
new file mode 100644
index 0000000..92d3468
--- /dev/null
+++ b/mapytex/calculus/random/core/str2.py
@@ -0,0 +1,65 @@
+
+from ...core.operator import is_operator
+from functools import partial
+from ...core.str2 import concurent_broadcast, lookforNumbers, pparser, missing_times, lookfor
+from ...core.coroutine import STOOOP
+from ...core.MO import moify_cor
+from ...core.tree import MutableTree
+from .leaf import look_for_rdleaf
+
+def rdstr2(sink):
+    """ Return a pipeline which parse random expression and with sink as endpoint
+
+    :example:
+    >>> from ...core.str2 import list_sink
+    >>> rdstr2list = rdstr2(list_sink)
+    >>> rdstr2list("{a}+{a*b}-2")
+    [<RdLeaf a>, '+', <RdLeaf a*b>, '+', <MOnumber -2>]
+    >>> rdstr2list("{a}({b}x+{c})")
+    [<RdLeaf a>, '*', [<RdLeaf b>, '*', <MOstr x>, '+', <RdLeaf c>]]
+    """
+    lfop = lookfor(is_operator)
+    operator_corout = partial(concurent_broadcast, lookfors=[lfop])
+
+    def pipeline(expression):
+        str2_corout = look_for_rdleaf(
+            lookforNumbers(operator_corout(
+                missing_times(moify_cor(pparser(sink)))))
+        )
+
+        for i in expression.replace(" ", ""):
+            str2_corout.send(i)
+        a = str2_corout.throw(STOOOP)
+
+        return a
+
+    return pipeline
+
+class RandomTree(MutableTree):
+    """ MutableTree that accept {a} syntax for random generation """
+
+    @classmethod
+    def from_str(cls, expression):
+        """ Initiate a random tree from a string that need to be parsed
+
+        :exemple:
+        >>> t = RandomTree.from_str("{b}*x+{c}")
+        >>> print(t)
+        +
+         > *
+         | > {b}
+         | > x
+         > {c}
+        >>> t = RandomTree.from_str("{a}*({b}*x+{c})")
+        >>> print(t)
+        *
+         > {a}
+         > +
+         | > *
+         | | > {b}
+         | | > x
+         | > {c}
+        """
+        str_2_mut_tree = rdstr2(cls.sink)
+        return str_2_mut_tree(expression)
+