diff --git a/pymath/random_expression.py b/pymath/random_expression.py
index 26dd4ee..44ce538 100644
--- a/pymath/random_expression.py
+++ b/pymath/random_expression.py
@@ -8,6 +8,11 @@ from .generic import flatten_list
 
 from .arithmetic import gcd
 
+def random_str(form, conditions = [], val_min = -10, val_max = 10):
+    """ Create a random string using RdExpression class  """
+    random_str_generator = RdExpression(form, conditions)
+    return random_str_generator(val_min, val_max)
+
 class RdExpression(object):
     """
 
@@ -132,22 +137,17 @@ def desc_rdExp(rdExp):
 
 
 if __name__ == '__main__':
-    form = "{a}*-14 / (2*{b}) / -23 / 4"
-    cond = ["{a} + {b} in [1, 2, 3, 4, 5]", "{a} not in [1]", "{b} not in [1]"]
-    rdExp1 = RdExpression(form, cond)
-    desc_rdExp(rdExp1)
-    rdExp2 = RdExpression(form)
-    desc_rdExp(rdExp2)
+    form = "({a};{b})"
+    cond = []
+    print(random_str(form, cond))
 
     form = "{a+a*10}*4 + {a} + 2*{b}"
     cond = ["{a} + {b} in [1, 2, 3, 4, 5]", "abs({a}) not in [1]", "{b} not in [1]", "gcd({a},{b}) == 1"]
-    rdExp3 = RdExpression(form, cond)
-    desc_rdExp(rdExp3)
+    print(random_str(form, cond))
 
     form = "{a+a*10}*4 + {a} + 2*{b}"
     cond = ["{a-b} + {b} in list(range(20))", "abs({a}) not in [1]", "{b} not in [1]", "gcd({a},{b}) == 1"]
-    rdExp3 = RdExpression(form, cond)
-    desc_rdExp(rdExp3)
+    print(random_str(form, cond))
 
     import doctest
     doctest.testmod()