fix: use list of dict keys to iterate, fix flake8 warnings

- py3 compatibility

schema_salad/ref_resolver.py

@@ -685,7 +685,7 @@ def _resolve_identity(self, document, loader, base_url):
     def _normalize_fields(self, document, loader):
         # type: (Dict[Text, Text], Loader) -> None
         # Normalize fields which are prefixed or full URIn to vocabulary terms
-        for d in document:
+        for d in list(document.keys()):
             d2 = loader.expand_url(d, u"", scoped_id=False, vocab_term=True)
             if d != d2:
                 document[d2] = document[d]

schema_salad/schema.py

@@ -9,16 +9,15 @@
 import avro.schema
 from . import validate
 import json
-# import urlparse
+
 from six.moves.urllib import parse
 import six
 import os
 
-if six.PY3: 
+if six.PY3:
     AvroSchemaFromJSONData = avro.schema.SchemaFromJSONData
-else:      
+else:
     AvroSchemaFromJSONData = avro.schema.make_avsc_object
-
 
 from avro.schema import Names, SchemaParseException
 from . import ref_resolver

setup.py

@@ -41,9 +41,10 @@
 # install_requires.append("avro")  # TODO: remove me once cwltool is
 # available in Debian Stable, Ubuntu 12.04 LTS
 
-extras_require={                # TODO: uncomment me, same conditions as above
-       ':python_version<"3"': ['avro'],
-       ':python_version>="3"': ['avro-python3']}
+
+extras_require={                  # TODO: uncomment me, same conditions as above
+    ':python_version<"3"': ['avro'],
+    ':python_version>="3"': ['avro-python3']}
 # extras_require = {}               # TODO: to be removed when the above is added
 
 setup(name='schema-salad',