diff --git a/mapytex/calculus/API/__init__.py b/mapytex/calculus/API/__init__.py
index 5db61aa..1b31d7d 100644
--- a/mapytex/calculus/API/__init__.py
+++ b/mapytex/calculus/API/__init__.py
@@ -61,8 +61,8 @@ Generate and compute like a student!
 
 >>> e = Expression.from_str("x^2*x*x^4")
 >>> e_simplified = e.simplify()
->>> print(e_simplified)
-x^7
+>>> e_simplified
+<Polynomial x^7>
 >>> for s in e_simplified.explain():
 ...    print(s)
 x^2 * x * x^4
@@ -72,8 +72,8 @@ x^7
 
 >>> e = Expression.from_str("2x+2+3x")
 >>> e_simplified = e.simplify()
->>> print(e_simplified)
-5x + 2
+>>> e_simplified
+<Linear 5x + 2>
 >>> for s in e_simplified.explain():
 ...    print(s)
 2x + 2 + 3x
@@ -83,8 +83,8 @@ x^7
 
 >>> e = Expression.from_str("1+2x^2+3x+4+5x")
 >>> e_simplified = e.simplify()
->>> print(e_simplified)
-5 + 2x^2 + 8x
+>>> e_simplified
+<Quadratic 5 + 2x^2 + 8x>
 >>> for s in e_simplified.explain():
 ...    print(s)
 1 + 2x^2 + 3x + 4 + 5x
diff --git a/mapytex/calculus/API/tokens/__init__.py b/mapytex/calculus/API/tokens/__init__.py
index e202939..2a0b4dd 100644
--- a/mapytex/calculus/API/tokens/__init__.py
+++ b/mapytex/calculus/API/tokens/__init__.py
@@ -23,27 +23,70 @@ __all__ = ["factory"]
 
 def factory(exp, name="", ancestor=None):
     """ Transform a Expression with on MathObject (from core) to a appropriate token (from API)
+
+    :example:
+    >>> from ..expression import Expression
+    >>> a = Expression(MOnumber(2))
+    >>> factory(a)
+    <Integer 2>
+    >>> a = Expression(MOnumber(2.5))
+    >>> factory(a)
+    <Decimal 2.5>
+    >>> a = Expression(MOFraction(2, 5))
+    >>> factory(a)
+    <Fraction 2 / 5>
+    >>> a = Expression(MOstr('x'))
+    >>> factory(a)
+    <Linear x>
+    >>> a = Expression(MOstrPower('x', 2))
+    >>> factory(a)
+    <Quadratic x^2>
+    >>> a = Expression(MOstrPower('x', 3))
+    >>> factory(a)
+    <Polynomial x^3>
+    >>> a = Expression(MOMonomial(3, 'x', 1))
+    >>> factory(a)
+    <Linear 3x>
+    >>> a = Expression(MOMonomial(3, 'x', 2))
+    >>> factory(a)
+    <Quadratic 3x^2>
+    >>> a = Expression(MOMonomial(3, 'x', 3))
+    >>> factory(a)
+    <Polynomial 3x^3>
     """
     mo = exp._tree
     if not isinstance(mo, MO):
         raise TypeError(f"Can't build Token from not computed Expression (got {mo})")
+
     if isinstance(mo, MOnumber):
         if isinstance(mo.value, int):
             return Integer(mo, name, ancestor)
         elif isinstance(mo.value, _Decimal):
             return Decimal(mo, name, ancestor)
-        else:
-            raise TypeError(f"Can't build from MOnumber ({mo}) neither int nor decimal")
+
+        raise TypeError(f"Can't build from MOnumber ({mo}) neither int nor decimal")
 
     elif isinstance(mo, MOFraction):
         if isinstance(mo._denominator, MOnumber) and \
                 isinstance(mo._numerator, MOnumber):
             return Fraction(mo, name, ancestor)
-        else:
-            raise TypeError(f"Can't build from MOFraction ({mo}) numerator and denominator are not MOnumber")
+
+        raise TypeError(f"Can't build from MOFraction ({mo}) numerator and denominator are not MOnumber")
 
     elif isinstance(mo, (MOstr, MOstrPower, MOMonomial, MOpolynomial)):
-        raise TypeError(f"Can't build Polynom yet")
+        if not isinstance(mo._variable, (MOstr, str)):
+            raise TypeError(f"Can't build Polynom over something else than a letter (got {mo._variable})")
+        if isinstance(mo, MOstr) or \
+                (isinstance(mo, MOMonomial) and mo.power.value == 1) or \
+                (isinstance(mo, MOpolynomial) and mo.power.value == 1):
+            return Linear(mo, name, ancestor)
+        elif (isinstance(mo, MOstrPower) and  mo.power.value == 2) or \
+            (isinstance(mo, MOMonomial) and mo.power.value == 2) or \
+            (isinstance(mo, MOpolynomial) and mo.power.value == 2):
+            return Quadratic(mo, name, ancestor)
+        else:
+            return Polynomial(mo, name, ancestor)
+
     else:
         raise TypeError(f"{type(mo)} is unknown MathObject")
 
diff --git a/mapytex/calculus/API/tokens/polynomial.py b/mapytex/calculus/API/tokens/polynomial.py
index ff8c9a6..d93ba71 100644
--- a/mapytex/calculus/API/tokens/polynomial.py
+++ b/mapytex/calculus/API/tokens/polynomial.py
@@ -19,10 +19,6 @@ class Polynomial(Token):
     """ Token representing a polynomial """
 
     def __init__(self, mo, name="", ancestor=None):
-        if not isinstance(mo, MOpolynomial):
-            raise TypeError
-        if  not isinstance(mo.value, int):
-            raise TypeError
 
         Token.__init__(self, mo, name, ancestor)
         self._mathtype = 'polynome'
@@ -48,10 +44,6 @@ class Linear(Token):
     """ Token representing a linear """
 
     def __init__(self, mo, name="", ancestor=None):
-        if not isinstance(mo, MOpolynomial):
-            raise TypeError
-        if  not isinstance(mo.value, int):
-            raise TypeError
 
         Token.__init__(self, mo, name, ancestor)
         self._mathtype = 'affine'
@@ -65,10 +57,6 @@ class Quadratic(Token):
     """ Token representing a quadratic """
 
     def __init__(self, mo, name="", ancestor=None):
-        if not isinstance(mo, MOpolynomial):
-            raise TypeError
-        if  not isinstance(mo.value, int):
-            raise TypeError
 
         Token.__init__(self, mo, name, ancestor)
         self._mathtype = 'polynome du 2nd degré'