diff --git a/il65/lexer.py b/il65/lexer.py
index d9bf7f377..9c28ea752 100644
--- a/il65/lexer.py
+++ b/il65/lexer.py
@@ -127,7 +127,7 @@ def t_inlineasm_lbrace(t):
 def t_inlineasm_rbrace(t):
     r"\}"
     t.lexer.level -= 1
-    #if closing brace, return code fragment
+    # if closing brace, return code fragment
     if t.lexer.level == 0:
         t.value = t.lexer.lexdata[t.lexer.code_start:t.lexer.lexpos-1]
         t.type = "INLINEASM"
@@ -285,5 +285,5 @@ lexer.error_function = error_function        # can override this
 
 if __name__ == "__main__":
     ply.lex.runmain()
-    #lexer = ply.lex.Lexer()
-    #ply.lex.runmain(lexer=lexer)
+    # lexer = ply.lex.Lexer()
+    # ply.lex.runmain(lexer=lexer)
diff --git a/il65/parse.py b/il65/parse.py
index c1763f93b..a9c2174e0 100644
--- a/il65/parse.py
+++ b/il65/parse.py
@@ -486,7 +486,7 @@ class Parser:
                     break    # the first import directive actually is not part of the header anymore
                 else:
                     raise self.PError("invalid directive")
-            break # no more directives, header parsing finished!
+            break  # no more directives, header parsing finished!
         self.prev_line()
         if not self.result.start_address:
             # set the proper default start address
@@ -844,7 +844,8 @@ class Parser:
             groups = match.groupdict()
             subname = groups["subname"]
             return self.parse_call_or_goto(subname, groups["arguments"], None, None, True)
-        match = re.fullmatch(r"(?P<outputs>[^\(]*\s*=)?\s*(?P<subname>[\S]+?)\s*(?P<preserve>!\s*[A-Z]*)?\s*(\((?P<arguments>.*)\))?\s*", line)
+        match = re.fullmatch(
+            r"(?P<outputs>[^\(]*\s*=)?\s*(?P<subname>[\S]+?)\s*(?P<preserve>!\s*[A-Z]*)?\s*(\((?P<arguments>.*)\))?\s*", line)
         if match:
             # subroutine call (not a goto) with possible output param assignment
             groups = match.groupdict()
diff --git a/il65/plyacc.py b/il65/plyacc.py
index 51fa983e3..9178ae0c5 100644
--- a/il65/plyacc.py
+++ b/il65/plyacc.py
@@ -244,7 +244,7 @@ def p_type_opt(p):
 def p_dimensions(p):
     """dimensions : INTEGER
                   | dimensions ',' INTEGER"""
-    if len(p)==2:
+    if len(p) == 2:
         p[0] = [p[1]]
     else:
         p[0] = p[1] + [p[3]]
@@ -480,7 +480,7 @@ parser = yacc()
 
 if __name__ == "__main__":
     import sys
-    file=sys.stdin  # open(sys.argv[1], "rU")
+    file = sys.stdin  # open(sys.argv[1], "rU")
     result = parser.parse(input=file.read()) or Module(None, SourceRef("@todo-sfile", 1, 1))
     print("RESULT")
-    print(result.nodes)
+    print(str(result))
diff --git a/il65/symbols.py b/il65/symbols.py
index af9a78898..4cb681068 100644
--- a/il65/symbols.py
+++ b/il65/symbols.py
@@ -702,6 +702,40 @@ class AstNode:
     def lineref(self) -> str:
         return "src l. " + str(self.sourceref.line)
 
+    def __str__(self) -> str:
+        def tostr(node: Any, level: int) -> str:
+            indent = "   "
+            clsname = node.__class__.__name__
+            attrs = []
+            try:
+                nvars = vars(node)
+            except TypeError:
+                if type(node) is str:
+                    sv = repr(node)
+                    if len(sv) > 20:
+                        sv = sv[:20] + "...'"
+                    return sv
+                return str(node)
+            for name, value in nvars.items():
+                if name == "sourceref":
+                    continue
+                if type(value) in (str, int, float, bool, type(None)):
+                    attrs.append((name, tostr(value, level+1)))
+            for name, value in nvars.items():
+                if type(value) is list:
+                    strvalue = "["
+                    strvalue += (",\n" + indent*(level+1)).join(tostr(v, level+1) for v in value) + "\n" + (1+level)*indent + "]"
+                    attrs.append((name, strvalue))
+            for name, value in nvars.items():
+                if name == "sourceref":
+                    continue
+                if type(value) is not list and type(value) not in (str, int, float, bool, type(None)):
+                    attrs.append((name, tostr(value, level+2)))
+            attrstr = ("\n" + indent*(1+level)).join("{} = {}".format(name, sv) for name, sv in attrs)
+            result = "\n" + indent * level + "<{0:s}  l={1:d}  c={2:d}".format(clsname, node.sourceref.line, node.sourceref.column)
+            return result + "{} |end {} l={:d}|>".format(attrstr, clsname, node.sourceref.line)
+        return tostr(self, 0)
+
 
 class Block(AstNode):
     _unnamed_block_labels = {}  # type: Dict[Block, str]
diff --git a/mypy.ini b/mypy.ini
index 8cc8b9027..f31a065a1 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -2,3 +2,6 @@
 follow_imports = normal
 ignore_missing_imports = True
 incremental = True
+
+[mypy-il65/parsetab.*]
+ignore_errors = True
diff --git a/setup.cfg b/setup.cfg
index f9d40e7e5..ee290141b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,3 +1,3 @@
 [pycodestyle]
 max-line-length = 140
-exclude = .git,__pycache__,.tox,docs,tests,build,dist
+exclude = .git,__pycache__,.tox,docs,tests,build,dist,parsetab.py