diff --git a/library/cadbiom/models/biosignal/translators/gt_visitors.py b/library/cadbiom/models/biosignal/translators/gt_visitors.py
index cd9b4cf760056d5021fcf5d6160b3c7f4152731c..1841c2f07edc70e524ecd57ebccc45c19a139cd8 100644
--- a/library/cadbiom/models/biosignal/translators/gt_visitors.py
+++ b/library/cadbiom/models/biosignal/translators/gt_visitors.py
@@ -41,7 +41,6 @@
 """
 Utilities for compiling conditions, event and constraints
 """
-#import sys
 from antlr3 import ANTLRStringStream, CommonTokenStream, RecognitionException
 
 from cadbiom.models.biosignal.translators.sigexpr_lexer import sigexpr_lexer
@@ -57,17 +56,17 @@ INACT = "_inac"
 UPDAT = "_update"
 
 
+def compile_cond(text, symb_table, error_reporter, deep=-1, message=""):
+    """Compile a condition expression to a tree representation
 
-def compile_cond(text, symb_table, error_reporter, deep = -1, message = ""):
-    """
-    Compile a condition expression to a tree representation
     @param text: string to be compiled
     @param symb_table: symbol table of the compiler
     @param error_reporter: use a CompilReporter for full information!!
     @param deep: optional - if >0 the compiler doesn't accept states
                 declared inside macro
+    @return: a tree representing the expression
     """
-    text_c = text+" $"
+    text_c = text + " $"
     reader = ANTLRStringStream(text_c)
     lexer = sigexpr_lexer(reader)
     parser = sigexpr_compiler(CommonTokenStream(lexer))
@@ -80,48 +79,51 @@ def compile_cond(text, symb_table, error_reporter, deep = -1, message = ""):
     parser.state_only = True
     try:
         tree = parser.sig_bool(symb_table)
-    except RecognitionException , exc:
+    except RecognitionException as exc:
         if error_reporter:
-            error_reporter.display( 'Error in condition: %s'%exc)
+            error_reporter.display("Error in condition: %s" % exc)
             parser.displayExceptionMessage(exc)
             return None
         else:
             raise exc
     return tree.exp
 
+
 def compile_constraint(const_txt, symb_table, error_reporter):
-    """
-    Compile a constraint expression to a tree representation
+    """Compile a constraint expression to a tree representation
+
     @param const_txt: string to be compiled
     @param symb_table: symbol table of the compiler
     @param error_reporter: output error messages
     @return: a tree representing the expression
     """
-    text_c = const_txt+" $"
+    text_c = const_txt + " $"
     reader = ANTLRStringStream(text_c)
     lexer = sigexpr_lexer(reader)
     parser = sigexpr_compiler(CommonTokenStream(lexer))
     parser.set_error_reporter(error_reporter)
     try:
         tree = parser.sig_expression(symb_table)
-    except RecognitionException , exc:
-        error_reporter.display('Error in constraints: %s'%exc)
+    except RecognitionException as exc:
+        error_reporter.display("Error in constraints: %s" % exc)
         parser.displayExceptionMessage(exc)
         return None
     return tree.exp
 
+
 def compile_event(text, symb_table, free_clocks, error_reporter):
-    """
-    Compile an event expression to a tree representation
+    """Compile an event expression to a tree representation
+
     @param text: string to be compiled
     @param symb_table: symbol table of the compiler
     @param free_clocks: boolean if true free clocks are collected
     @param error_reporter: output error messages
-    @return: a triple exp, se, fc where exp is the event expression,
-            se the state events (s#> ..) used and
-            fc is the free clocks used in the event expression.
+    @return: a triple exp, se, fc
+        where exp is the event expression,
+        se the state events (s#> ..) used and
+        fc is the free clocks used in the event expression.
     """
-    text_c = text+' $'
+    text_c = text + " $"
     reader = ANTLRStringStream(text_c)
     lexer = sigexpr_lexer(reader)
     # default options on compiler (state_only = False)
@@ -132,9 +134,8 @@ def compile_event(text, symb_table, free_clocks, error_reporter):
     parser.state_only_in_bool = True
     try:
         tree = parser.sig_expression(symb_table)
-    except RecognitionException , exc:
-        error_reporter.display('Error in event: %s'%exc)
+    except RecognitionException as exc:
+        error_reporter.display("Error in event: %s" % exc)
         parser.displayExceptionMessage(exc)
         return None
     return tree.exp, parser.state_events, parser.free_clocks
-