diff --git a/auto_py2to3/libs/lib2to3/btm_utils.py b/auto_py2to3/libs/lib2to3/btm_utils.py
index c78fea1c2c3f040e29b33945218b048a932262cd..dc16d19c188766ca481d8a669198669c48972f8e 100644
--- a/auto_py2to3/libs/lib2to3/btm_utils.py
+++ b/auto_py2to3/libs/lib2to3/btm_utils.py
@@ -19,8 +19,8 @@ class MinNode(object):
     pattern tree during the conversion to sets of leaf-to-root
     subpatterns"""
 
-    def __init__(self, type=None, name=None):
-        self.type = type
+    def __init__(self, _type=None, name=None):
+        self.type = _type
         self.name = name
         self.children = []
         self.leaf = False
@@ -220,9 +220,7 @@ def reduce_tree(node, parent=None):
                 # reduce to a single occurrence i.e. do nothing
                 pass
             else:
-                # TODO: handle {min, max} repeaters
                 raise NotImplementedError
-                pass
 
         # add children
         if details_node and new_node is not None:
diff --git a/auto_py2to3/libs/lib2to3/fixer_base.py b/auto_py2to3/libs/lib2to3/fixer_base.py
index 7e14be67ac5b48dcd8409e7e00758091a548565e..79f69ee39c4ee481876361e146a4fddb6d13307c 100644
--- a/auto_py2to3/libs/lib2to3/fixer_base.py
+++ b/auto_py2to3/libs/lib2to3/fixer_base.py
@@ -7,6 +7,8 @@
 import itertools
 
 # Local imports
+from abc import ABC
+
 from .patcomp import PatternCompiler
 from . import pygram
 from .fixer_util import does_tree_import
@@ -42,7 +44,7 @@ class BaseFix(object):
     # manually
 
     # Shortcut for access to Python grammar symbols
-    syms = pygram.python_symbols
+    sym_s = pygram.python_symbols
 
     def __init__(self, options, log):
         """Initializer.  Subclass may override.
@@ -52,6 +54,7 @@ class BaseFix(object):
             that could be used to customize the fixer through the command line.
             log: a list to append warnings and other messages to.
         """
+        self.first_log = False
         self.options = options
         self.log = log
         self.compile_pattern()
@@ -115,7 +118,6 @@ class BaseFix(object):
 
     def log_message(self, message):
         if self.first_log:
-            self.first_log = False
             self.log.append("### In file %s ###" % self.filename)
         self.log.append(message)
 
@@ -166,15 +168,18 @@ class BaseFix(object):
         pass
 
 
-class ConditionalFix(BaseFix):
+class ConditionalFix(BaseFix, ABC):
     """ Base class for fixers which not execute if an import is found. """
 
     # This is the name of the import which, if found, will cause the test to be skipped
     skip_on = None
 
+    def __init__(self, options, log):
+        super().__init__(options, log)
+        self._should_skip = None
+
     def start_tree(self, *args):
         super(ConditionalFix, self).start_tree(*args)
-        self._should_skip = None
 
     def should_skip(self, node):
         if self._should_skip is not None:
diff --git a/auto_py2to3/libs/lib2to3/fixer_util.py b/auto_py2to3/libs/lib2to3/fixer_util.py
index 29d97ce4c950b0f01dbe52fd1bba928a63b4ed10..76d7e64da2b1532ee9ddd22f048ac166b39fd979 100644
--- a/auto_py2to3/libs/lib2to3/fixer_util.py
+++ b/auto_py2to3/libs/lib2to3/fixer_util.py
@@ -127,11 +127,6 @@ def ListComp(xp, fp, it, test=None):
 def FromImport(package_name, name_leafs):
     """ Return an import statement in the form:
         from package import name_leafs"""
-    # XXX: May not handle dotted imports properly (eg, package_name='foo.bar')
-    # assert package_name == '.' or '.' not in package_name, "FromImport has "\
-    #       "not been tested with dotted package names -- use at your own "\
-    #       "peril!"
-
     for leaf in name_leafs:
         # Pull the leaves out of their old tree
         leaf.remove()
@@ -221,31 +216,10 @@ def attr_chain(obj, attr):
     Yields:
         Each successive object in the chain.
     """
-    next = getattr(obj, attr)
-    while next:
-        yield next
-        next = getattr(next, attr)
-
-
-p0 = """for_stmt< 'for' any 'in' node=any ':' any* >
-        | comp_for< 'for' any 'in' node=any any* >
-     """
-p1 = """
-power<
-    ( 'iter' | 'list' | 'tuple' | 'sorted' | 'set' | 'sum' |
-      'any' | 'all' | 'enumerate' | (any* trailer< '.' 'join' >) )
-    trailer< '(' node=any ')' >
-    any*
->
-"""
-p2 = """
-power<
-    ( 'sorted' | 'enumerate' )
-    trailer< '(' arglist<node=any any*> ')' >
-    any*
->
-"""
-pats_built = False
+    _next = getattr(obj, attr)
+    while _next:
+        yield _next
+        _next = getattr(_next, attr)
 
 
 def in_special_context(node):
@@ -254,7 +228,25 @@ def in_special_context(node):
         or an iterator).
         See test_map_nochange in test_fixers.py for some examples and tests.
         """
-    global p0, p1, p2, pats_built
+    p0 = """for_stmt< 'for' any 'in' node=any ':' any* >
+            | comp_for< 'for' any 'in' node=any any* >
+         """
+    p1 = """
+    power<
+        ( 'iter' | 'list' | 'tuple' | 'sorted' | 'set' | 'sum' |
+          'any' | 'all' | 'enumerate' | (any* trailer< '.' 'join' >) )
+        trailer< '(' node=any ')' >
+        any*
+    >
+    """
+    p2 = """
+    power<
+        ( 'sorted' | 'enumerate' )
+        trailer< '(' arglist<node=any any*> ')' >
+        any*
+    >
+    """
+    pats_built = False
     if not pats_built:
         p0 = patcomp.compile_pattern(p0)
         p1 = patcomp.compile_pattern(p1)
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_apply.py b/auto_py2to3/libs/lib2to3/fixes/fix_apply.py
index d3b5e94819c82d07a6ac3b1a3e69540959025427..4a6052e56bc2073797e5f140b02b08a2d5e25f01 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_apply.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_apply.py
@@ -30,7 +30,7 @@ class FixApply(fixer_base.BaseFix):
     """
 
     def transform(self, node, results):
-        syms = self.syms
+        sym_s = self.syms
         assert results
         func = results["func"]
         args = results["args"]
@@ -48,8 +48,8 @@ class FixApply(fixer_base.BaseFix):
             return  # Make no change.
         prefix = node.prefix
         func = func.clone()
-        if (func.type not in (token.NAME, syms.atom) and
-            (func.type != syms.power or
+        if (func.type not in (token.NAME, sym_s.atom) and
+            (func.type != sym_s.power or
              func.children[-2].type == token.DOUBLESTAR)):
             # Need to parenthesize
             func = parenthesize(func)
@@ -64,8 +64,5 @@ class FixApply(fixer_base.BaseFix):
             l_newargs.extend([Comma(),
                               pytree.Leaf(token.DOUBLESTAR, "**"),
                               kwds])
-            l_newargs[-2].prefix = " "  # that's the ** token
-        # XXX Sometimes we could be cleverer, e.g. apply(f, (x, y) + t)
-        # can be translated into f(x, y, *t) instead of f(*(x, y) + t)
-        # new = pytree.Node(syms.power, (func, ArgList(l_newargs)))
+            l_newargs[-2].prefix = " "
         return Call(func, l_newargs, prefix=prefix)
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_dict.py b/auto_py2to3/libs/lib2to3/fixes/fix_dict.py
index c029bfccee98b4c885bf6ac0814013f0b0720fe4..776b7debafafd3054912f13bc6be746fd9b566dc 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_dict.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_dict.py
@@ -54,7 +54,7 @@ class FixDict(fixer_base.BaseFix):
         head = results["head"]
         method = results["method"][0]  # Extract node for method name
         tail = results["tail"]
-        syms = self.syms
+        sym_s = self.syms
         method_name = method.value
         isiter = method_name.startswith("iter")
         isview = method_name.startswith("view")
@@ -64,17 +64,17 @@ class FixDict(fixer_base.BaseFix):
         head = [n.clone() for n in head]
         tail = [n.clone() for n in tail]
         special = not tail and self.in_special_context(node, isiter)
-        args = head + [pytree.Node(syms.trailer,
+        args = head + [pytree.Node(sym_s.trailer,
                                    [Dot(),
                                     Name(method_name,
                                          prefix=method.prefix)]),
                        results["parens"].clone()]
-        new = pytree.Node(syms.power, args)
+        new = pytree.Node(sym_s.power, args)
         if not (special or isview):
             new.prefix = ""
             new = Call(Name("iter" if isiter else "list"), [new])
         if tail:
-            new = pytree.Node(syms.power, [new] + tail)
+            new = pytree.Node(sym_s.power, [new] + tail)
         new.prefix = node.prefix
         return new
 
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_except.py b/auto_py2to3/libs/lib2to3/fixes/fix_except.py
index 6068755197177600b7e3640fedb5f5d51aeb5107..0fd50356f219d0ade318d5462545704c5518c80f 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_except.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_except.py
@@ -25,12 +25,12 @@ The following cases will be converted:
 from .. import pytree
 from ..pgen2 import token
 from .. import fixer_base
-from ..fixer_util import Assign, Attr, Name, is_tuple, is_list, syms
+from ..fixer_util import Assign, Attr, Name, is_tuple, is_list, sym_s
 
 
 def find_excepts(nodes):
     for i, n in enumerate(nodes):
-        if n.type == syms.except_clause:
+        if n.type == sym_s.except_clause:
             if n.children[0].value == 'except':
                 yield (n, nodes[i + 2])
 
@@ -47,7 +47,7 @@ class FixExcept(fixer_base.BaseFix):
     """
 
     def transform(self, node, results):
-        syms = self.syms
+        sym_s = self.syms
 
         tail = [n.clone() for n in results["tail"]]
 
@@ -70,6 +70,7 @@ class FixExcept(fixer_base.BaseFix):
                     #  and indents
                     # TODO(cwinter) suite-cleanup
                     suite_stmts = e_suite.children
+                    i = 0
                     for i, stmt in enumerate(suite_stmts):
                         if isinstance(stmt, pytree.Node):
                             break
@@ -81,7 +82,6 @@ class FixExcept(fixer_base.BaseFix):
                     else:
                         assign = Assign(target, new_N)
 
-                    # TODO(cwinter) stopgap until children becomes a smart list
                     for child in reversed(suite_stmts[:i]):
                         e_suite.insert_child(0, child)
                     e_suite.insert_child(i, assign)
@@ -90,6 +90,5 @@ class FixExcept(fixer_base.BaseFix):
                     # not so much.
                     N.prefix = " "
 
-        # TODO(cwinter) fix this when children becomes a smart list
         children = [c.clone() for c in node.children[:3]] + try_cleanup + tail
         return pytree.Node(node.type, children)
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_exec.py b/auto_py2to3/libs/lib2to3/fixes/fix_exec.py
index ab921ee80cdf366532f027b2549e5bcba55a4fd5..2633e6d89175a18bd380618a77c53b19091156ab 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_exec.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_exec.py
@@ -25,7 +25,7 @@ class FixExec(fixer_base.BaseFix):
 
     def transform(self, node, results):
         assert results
-        syms = self.syms
+        sym_s = self.syms
         a = results["a"]
         b = results.get("b")
         c = results.get("c")
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_execfile.py b/auto_py2to3/libs/lib2to3/fixes/fix_execfile.py
index b6c786fd4e8b6a141ab3619ba2b2576db158fcd4..8bb9e1ea3bc591bf7e02a74afe92d90f368400ea 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_execfile.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_execfile.py
@@ -24,8 +24,8 @@ class FixExecfile(fixer_base.BaseFix):
     def transform(self, node, results):
         assert results
         filename = results["filename"]
-        globals = results.get("globals")
-        locals = results.get("locals")
+        tmp_globals = results.get("globals")
+        tmp_locals = results.get("locals")
 
         # Copy over the prefix from the right parentheses end of the execfile
         # call.
@@ -46,8 +46,8 @@ class FixExecfile(fixer_base.BaseFix):
         compile_call = Call(Name("compile"), compile_args, "")
         # Finally, replace the execfile call with an exec call.
         args = [compile_call]
-        if globals is not None:
-            args.extend([Comma(), globals.clone()])
-        if locals is not None:
-            args.extend([Comma(), locals.clone()])
+        if tmp_globals is not None:
+            args.extend([Comma(), tmp_globals.clone()])
+        if tmp_locals is not None:
+            args.extend([Comma(), tmp_locals.clone()])
         return Call(Name("exec"), args, prefix=node.prefix)
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_has_key.py b/auto_py2to3/libs/lib2to3/fixes/fix_has_key.py
index 439708c9923404312dfabb964615062ea32c0aea..d42dbdf91e8a1e7f04a84ff76957937c639bb984 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_has_key.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_has_key.py
@@ -70,8 +70,8 @@ class FixHasKey(fixer_base.BaseFix):
 
     def transform(self, node, results):
         assert results
-        syms = self.syms
-        if (node.parent.type == syms.not_test and
+        sym_s = self.syms
+        if (node.parent.type == sym_s.not_test and
             self.pattern.match(node.parent)):
             # Don't transform a node matching the first alternative of the
             # pattern when its parent matches the second alternative
@@ -84,26 +84,26 @@ class FixHasKey(fixer_base.BaseFix):
         after = results.get("after")
         if after:
             after = [n.clone() for n in after]
-        if arg.type in (syms.comparison, syms.not_test, syms.and_test,
-                        syms.or_test, syms.test, syms.lambdef, syms.argument):
+        if arg.type in (sym_s.comparison, sym_s.not_test, sym_s.and_test,
+                        sym_s.or_test, sym_s.test, sym_s.lambdef, sym_s.argument):
             arg = parenthesize(arg)
         if len(before) == 1:
             before = before[0]
         else:
-            before = pytree.Node(syms.power, before)
+            before = pytree.Node(sym_s.power, before)
         before.prefix = " "
         n_op = Name("in", prefix=" ")
         if negation:
             n_not = Name("not", prefix=" ")
-            n_op = pytree.Node(syms.comp_op, (n_not, n_op))
-        new = pytree.Node(syms.comparison, (arg, n_op, before))
+            n_op = pytree.Node(sym_s.comp_op, (n_not, n_op))
+        new = pytree.Node(sym_s.comparison, (arg, n_op, before))
         if after:
             new = parenthesize(new)
-            new = pytree.Node(syms.power, (new,) + tuple(after))
-        if node.parent.type in (syms.comparison, syms.expr, syms.xor_expr,
-                                syms.and_expr, syms.shift_expr,
-                                syms.arith_expr, syms.term,
-                                syms.factor, syms.power):
+            new = pytree.Node(sym_s.power, (new,) + tuple(after))
+        if node.parent.type in (sym_s.comparison, sym_s.expr, sym_s.xor_expr,
+                                sym_s.and_expr, sym_s.shift_expr,
+                                sym_s.arith_expr, sym_s.term,
+                                sym_s.factor, sym_s.power):
             new = parenthesize(new)
         new.prefix = prefix
         return new
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_raise.py b/auto_py2to3/libs/lib2to3/fixes/fix_raise.py
index d870d14a202fbee2374cdb5a1e558483dd1f927e..e4d1e6ea4bdcef8b70edf5ecdd7cfb4fab837a19 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_raise.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_raise.py
@@ -36,7 +36,7 @@ class FixRaise(fixer_base.BaseFix):
     """
 
     def transform(self, node, results):
-        syms = self.syms
+        sym_s = self.syms
 
         exc = results["exc"].clone()
         if exc.type == token.STRING:
@@ -59,7 +59,7 @@ class FixRaise(fixer_base.BaseFix):
 
         if "val" not in results:
             # One-argument raise
-            new = pytree.Node(syms.raise_stmt, [Name("raise"), exc])
+            new = pytree.Node(sym_s.raise_stmt, [Name("raise"), exc])
             new.prefix = node.prefix
             return new
 
@@ -81,10 +81,10 @@ class FixRaise(fixer_base.BaseFix):
             if val.type != token.NAME or val.value != "None":
                 e = Call(exc, args)
             with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])]
-            new = pytree.Node(syms.simple_stmt, [Name("raise")] + with_tb)
+            new = pytree.Node(sym_s.simple_stmt, [Name("raise")] + with_tb)
             new.prefix = node.prefix
             return new
         else:
-            return pytree.Node(syms.raise_stmt,
+            return pytree.Node(sym_s.raise_stmt,
                                [Name("raise"), Call(exc, args)],
                                prefix=node.prefix)
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_throw.py b/auto_py2to3/libs/lib2to3/fixes/fix_throw.py
index b340b4964f57a858f0f6940967c8671f7f233d28..ec06925bc5e0ae4dc6b5e9733818c4cc71460a40 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_throw.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_throw.py
@@ -25,7 +25,7 @@ class FixThrow(fixer_base.BaseFix):
     """
 
     def transform(self, node, results):
-        syms = self.syms
+        sym_s = self.syms
 
         exc = results["exc"].clone()
         if exc.type is token.STRING:
@@ -52,6 +52,6 @@ class FixThrow(fixer_base.BaseFix):
 
             e = Call(exc, args)
             with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])]
-            throw_args.replace(pytree.Node(syms.power, with_tb))
+            throw_args.replace(pytree.Node(sym_s.power, with_tb))
         else:
             throw_args.replace(Call(exc, args))
diff --git a/auto_py2to3/libs/lib2to3/fixes/fix_tuple_params.py b/auto_py2to3/libs/lib2to3/fixes/fix_tuple_params.py
index 1319747e1de42be03f53d2348b44f869b4592652..6b670b3fdb8f4d9fcf035e5acab77c11ea1ccd38 100644
--- a/auto_py2to3/libs/lib2to3/fixes/fix_tuple_params.py
+++ b/auto_py2to3/libs/lib2to3/fixes/fix_tuple_params.py
@@ -94,7 +94,6 @@ class FixTupleParams(fixer_base.BaseFix):
         for line in new_lines:
             line.parent = suite[0]
 
-        # TODO(cwinter) suite-cleanup
         after = start
         if start == 0:
             new_lines[0].prefix = " "