@@ -30,6 +30,7 @@ pip install -e .
 ```
 
 ## Testing
+
 Testing is done using tox. The config can be found in `tox.ini` within the python directory of the iceberg project.
 
 ```
 
@@ -20,11 +20,8 @@
 
 class CloseableIterable(collections.Iterator):
 
-    def next(self):
-        raise NotImplementedError()
-
     def __next__(self):
-        return self.next()
+        raise NotImplementedError()
 
     def close(self):
         raise NotImplementedError()
@@ -58,7 +58,7 @@ def fields(self):
     def java_classes(self):
         if self.__java_classes is None:
             self.__java_classes
-        for i, field in enumerate(self.__fields):
+        for field in self.__fields:
             source_type = self.schema.find_type(field.source_id)
             result = field.transform().get_result_by_type(source_type)
             self.__java_classes.append(result.type_id.java_class())
 
@@ -403,7 +403,7 @@ def struct(self, struct, field_results):
         length = len(struct.fields)
         new_ids = list()
 
-        for i in range(length):
+        for _ in range(length):
             new_ids.append(self.next_id())
 
         new_fields = list()
 
@@ -203,8 +203,7 @@ def convert_map_type(avro_field, next_id=None):
         avro_field_type = avro_field.get(AvroToIceberg.FIELD_TYPE_PROP)
         avro_logical_type = avro_field.get(AvroToIceberg.FIELD_LOGICAL_TYPE_PROP)
         if avro_field_type != "array" or avro_logical_type != "map":
-            raise RuntimeError("Avro type must be array and logical type must be map: %s" % (avro_field_type,
-                                                                                             avro_logical_type))
+            raise RuntimeError("Avro type must be array and logical type must be map: %s" % avro_logical_type)
         is_optional = False
         items = avro_field.get(AvroToIceberg.FIELD_ITEMS_PROP)
         for field in items.get(AvroToIceberg.FIELD_FIELDS_PROP, list()):
 
@@ -50,4 +50,4 @@ def default_warehouse_location(self, conf, database, table):
         if warehouse_location is None:
             raise RuntimeError("Warehouse location is not set: hive.metastore.warehouse.dir=null")
 
-        return "%s/%s.db/%s".format(warehouse_location, database, table)
+        return f"{warehouse_location}/{database}.db/{table}"
@@ -37,7 +37,7 @@ def copy_partition_data(spec, partition_data, reuse):
         if data is None:
             data = DataFiles.new_partition_data(spec)
 
-        for i, field in enumerate(spec.fields):
+        for i, _ in enumerate(spec.fields):
             data.set(i, partition_data.get(i))
 
         return data
 
@@ -182,7 +182,7 @@ def close(self):
     def flush(self):
         pass
 
-    def next(self):
+    def __next__(self):
         return next(self.readline())
 
     def read(self, n=0):
@@ -251,6 +251,3 @@ def __exit__(self, exc_type, exc_val, exc_tb):
 
     def __iter__(self):
         return self
-
-    def __next__(self):
-        return self.next()
@@ -184,7 +184,7 @@ def from_partition_summaries(self, snapshots):
                     or str_as_bool(snap.summary.get(SnapshotSummary.PARTITION_SUMMARY_PROP, "false")):
                 return None
 
-            for key, val in snap.summary.items():
+            for key, _ in snap.summary.items():
                 if key.startswith(SnapshotSummary.CHANGED_PARTITION_PREFIX):
                     part_key = key[len(SnapshotSummary.CHANGED_PARTITION_PREFIX):]
                     # part = dict(entry.split("=") for entry in val.split(","))
 
@@ -40,6 +40,12 @@
                       'pandas',
                       'pyarrow'
                       ],
+    extras_require={
+        "dev": [
+            "tox-travis==0.12",
+            "virtualenv<20.0.0",
+        ],
+    },
     setup_requires=['setupmeta'],
     license="Apache License 2.0",
     classifiers=[