diff --git a/REQUIREMENTS b/REQUIREMENTS
index 2853901..0b43b90 100644
--- a/REQUIREMENTS
+++ b/REQUIREMENTS
@@ -5,3 +5,4 @@ PyYAML
 Jinja2
 argcomplete
 networkx
+six
diff --git a/examples/model-correlations/src/cdf.py b/examples/model-correlations/src/cdf.py
index f25826b..0bee7e7 100644
--- a/examples/model-correlations/src/cdf.py
+++ b/examples/model-correlations/src/cdf.py
@@ -25,4 +25,4 @@
 data.sort()
 for i, x in enumerate(data):
     cdf = float(i)/len(data)
-    print x, "%0.4f" % cdf
+    print(x, "%0.4f" % cdf)
diff --git a/examples/model-correlations/src/correlation.py b/examples/model-correlations/src/correlation.py
index fe32e7e..fbb2aa6 100644
--- a/examples/model-correlations/src/correlation.py
+++ b/examples/model-correlations/src/correlation.py
@@ -2,7 +2,6 @@
 """
 
 import sys
-import csv
 import math
 
 # use headless matplotlib
@@ -33,4 +32,4 @@
 for i, j in zip(x, y):
     r += (i - xave)/xsig * (j - yave)/ysig
 r /= len(x) - 1
-print r
+print(r)
diff --git a/examples/sp500/code/parse_sp500.py b/examples/sp500/code/parse_sp500.py
index 676a0e9..229c906 100644
--- a/examples/sp500/code/parse_sp500.py
+++ b/examples/sp500/code/parse_sp500.py
@@ -5,7 +5,7 @@
 
 # read in html data
 with open(sys.argv[1]) as stream:
-    soup = BeautifulSoup(stream.read())
+    soup = BeautifulSoup(stream.read(), 'lxml')
 
 # extract the table into a csv
 writer = csv.writer(sys.stdout)
diff --git a/examples/sp500/flo.yaml b/examples/sp500/flo.yaml
index d813122..45ece8f 100644
--- a/examples/sp500/flo.yaml
+++ b/examples/sp500/flo.yaml
@@ -8,12 +8,12 @@ tasks:
     creates: "{{input_name}}"
     command:
       - mkdir -p $(dirname {{creates}})
-      - wget http://en.wikipedia.org/wiki/List_of_S%26P_500_companies -O {{creates}}
+      - wget http://en.wikipedia.org/wiki/List_of_S%26P_500_companies --no-check-certificate -O {{creates}}
 
   # extract the data
   -
     creates: data/sp500.csv
-    depends: 
+    depends:
       - code/parse_sp500.py
       - "{{input_name}}"
-    command: python {{depends|join(' ')}} > {{creates}}
\ No newline at end of file
+    command: python {{depends|join(' ')}} > {{creates}}
diff --git a/flo/commands/__init__.py b/flo/commands/__init__.py
index a320aa4..511223d 100644
--- a/flo/commands/__init__.py
+++ b/flo/commands/__init__.py
@@ -43,9 +43,9 @@ def run_subcommand(args):
     """This function runs the command that is selected by this particular
     subcommand parser.
     """
-    command = args.__dict__.pop("command")
     try:
+        command = args.__dict__.pop("command")
         command.execute(**args.__dict__)
-    except CommandLineException, error:
+    except (CommandLineException, KeyError) as error:
         print(colors.red(error))
         sys.exit(getattr(error, 'exit_code', 1))
diff --git a/flo/commands/status.py b/flo/commands/status.py
index 7ebc109..0881a01 100644
--- a/flo/commands/status.py
+++ b/flo/commands/status.py
@@ -1,5 +1,5 @@
-import BaseHTTPServer
-import SocketServer
+from six.moves import BaseHTTPServer
+from six.moves import socketserver
 import socket
 
 from .run import Command as RunCommand
@@ -40,8 +40,8 @@ def serve_status_page(self, port):
         Handler.task_graph = self.task_graph
         print("Starting server at http://localhost:%d" % port)
         try:
-            httpd = SocketServer.TCPServer(("", port), Handler)
-        except socket.error, error:
+            httpd = socketserver.TCPServer(("", port), Handler)
+        except socket.error as error:
             raise CommandLineException(error.strerror)
         try:
             httpd.serve_forever()
diff --git a/flo/exceptions.py b/flo/exceptions.py
index f3e1297..e8d3571 100644
--- a/flo/exceptions.py
+++ b/flo/exceptions.py
@@ -1,5 +1,6 @@
 import yaml
 import jinja2
+import six
 
 
 class CommandLineException(Exception):
@@ -75,7 +76,7 @@ def __init__(self, template_string, error, **context_dict):
 
     def __str__(self):
         context_str = "{\n"
-        for k, v in self.context_dict.iteritems():
+        for k, v in six.iteritems(self.context_dict):
             context_str += "%s%s: %s,\n" % (self.tab, k, v)
         context_str += "}"
         msg = "\n\nContext:\n\n%s" % self.indent(context_str)
diff --git a/flo/logger.py b/flo/logger.py
index 4944106..91ea5d9 100644
--- a/flo/logger.py
+++ b/flo/logger.py
@@ -13,20 +13,27 @@
 # achieves exactly what we want, albeit not using the standard
 # library. If you have other ideas for how to do this, check out the
 # code before issue #53 was resolved.
-class Logger(file):
+# class Logger(file):
+class Logger():
     """Log output to stdout in color and to a log file in plain text.
     """
+    log_file = None
+
     def __init__(self, task_graph):
-        super(Logger, self).__init__(task_graph.abs_log_path, 'w')
+        self.log_file = open(task_graph.abs_log_path, 'w')
 
     def write(self, content):
+        if isinstance(content, bytes):
+            content = content.decode()
         sys.stdout.write(content)
         sys.stdout.flush()
-        super(Logger, self).write(colorless(content))
+        self.log_file.write(colorless(content))
 
     def info(self, content):
         self.write(content + '\n')
 
+    def close(self):
+        self.log_file.close()
 
 # _logger is a singleton instance of the logger that is a local cache
 # of the one and only logger instance for all TaskGraphs. This is
diff --git a/flo/parser.py b/flo/parser.py
index b0cee83..3c3019a 100644
--- a/flo/parser.py
+++ b/flo/parser.py
@@ -91,7 +91,7 @@ def get_task_kwargs_list(config=None):
         config_yaml = yaml.load_all(stream.read())
     try:
         return config_yaml2task_kwargs_list(config_yaml)
-    except yaml.constructor.ConstructorError, error:
+    except yaml.constructor.ConstructorError as error:
         raise exceptions.YamlError(config_path, error)
 
 
diff --git a/flo/resources/base.py b/flo/resources/base.py
index 70dabaa..75f954c 100644
--- a/flo/resources/base.py
+++ b/flo/resources/base.py
@@ -72,7 +72,12 @@ def get_stream_state(self, stream, block_size=2**20):
             data = stream.read(block_size)
             if not data:
                 break
-            state.update(data)
+            try:
+                state.update(data)
+            except TypeError:
+                # Assuming this is caused by getting Unicode
+                # Unicode must be encoded before hashing
+                state.update(data.encode('utf8'))
         return state.hexdigest()
 
     def get_previous_state(self):
diff --git a/flo/tasks/graph.py b/flo/tasks/graph.py
index e00c060..80416b9 100644
--- a/flo/tasks/graph.py
+++ b/flo/tasks/graph.py
@@ -7,6 +7,8 @@
 import glob
 from distutils.util import strtobool
 import json
+import six
+from six.moves import input
 
 import networkx as nx
 
@@ -106,7 +108,8 @@ def iter_tasks(self, tasks=None):
             if task in source_tasks:
                 distance = 0
             else:
-                distance = max(map(distances.get, task.upstream_tasks)) + 1
+                distance = max([distances.get(x)
+                                for x in task.upstream_tasks]) + 1
             distances[task] = distance
             horizon.remove(task)
             horizon_set.discard(task)
@@ -119,7 +122,7 @@ def iter_tasks(self, tasks=None):
         # now create a decorated list of based on the distance and
         # ordering in the YAML file
         decorated_list = []
-        for task, distance in distances.iteritems():
+        for task, distance in six.iteritems(distances):
             decorated_list.append((
                 distance, self.task_list.index(task), task,
             ))
@@ -191,7 +194,7 @@ def subgraph_needed_for(self, start_at, end_at):
         new graph.
         """
         assert start_at or end_at, "one of {start_at,end_at} must be a task id"
-        start, end = map(self.task_dict.get, [start_at, end_at])
+        start, end = [self.task_dict.get(start_at), self.task_dict.get(end_at)]
         if None in [start, end]:
             graph = self.get_networkx_graph()
             if start:
@@ -273,7 +276,7 @@ def get_user_clean_confirmation(self, task_list=None,
             self.logger.info(green(self.internals_path))
         for task in task_list:
             self.logger.info(task.creates_message())
-        yesno = raw_input(colors.red("Delete aforementioned files? [Y/n] "))
+        yesno = input(colors.red("Delete aforementioned files? [Y/n] "))
         if yesno == '':
             yesno = 'y'
         return strtobool(yesno)
@@ -377,7 +380,7 @@ def _run_helper(self, starting_tasks, do_run_func, mock_run):
                 else:
                     try:
                         task.timed_run()
-                    except (KeyboardInterrupt, ShellError), error:
+                    except (KeyboardInterrupt, ShellError) as error:
                         self.save_state(
                             override_resource_states={task.name: ''},
                         )
@@ -432,7 +435,7 @@ def read_from_storage(self, storage_location):
     def write_to_storage(self, dictionary, storage_location):
         with open(storage_location, 'w') as stream:
             writer = csv.writer(stream)
-            for item in dictionary.iteritems():
+            for item in six.iteritems(dictionary):
                 writer.writerow(item)
 
     def get_state_from_storage(self, resource):
@@ -453,7 +456,7 @@ def _load_state(self):
         )
 
         # typecast the task_durations
-        for task_id, duration in self.task_durations.iteritems():
+        for task_id, duration in six.iteritems(self.task_durations):
             self.task_durations[task_id] = float(duration)
 
     def save_state(self, override_resource_states=None):
@@ -469,7 +472,7 @@ def save_state(self, override_resource_states=None):
         # CSV. this is important for situations where a subgraph is
         # selected to run
         after_resource_states = self.read_from_storage(self.abs_state_path)
-        for name, resource in self.resource_dict.iteritems():
+        for name, resource in six.iteritems(self.resource_dict):
             after_resource_states[name] = resource.get_current_state()
 
         # if override states are provided, update the resources
diff --git a/flo/tasks/task.py b/flo/tasks/task.py
index 30bcd47..79fe2c4 100644
--- a/flo/tasks/task.py
+++ b/flo/tasks/task.py
@@ -1,6 +1,7 @@
 import os
 import time
-import StringIO
+import six
+from six import StringIO
 import copy
 
 from ..exceptions import InvalidTaskDefinition, CommandLineException
@@ -10,13 +11,18 @@
 from .. import templates
 from ..types import UniqueOrderedList
 
+if six.PY2:
+    str_types = (str, unicode)
+else:
+    str_types = str
+
 
 def _cast_as_list(obj):
     if isinstance(obj, (list, tuple)):
         return obj
     elif obj is None:
         return []
-    elif isinstance(obj, (str, unicode)):
+    elif isinstance(obj, str_types):
         return [obj]
     else:
         raise TypeError("unexpected type passed to _cast_as_list")
@@ -39,7 +45,7 @@ def __init__(self, graph, creates=None, depends=None,
                 "every task must define a `creates`",
                 self.yaml_data,
             )
-        if not isinstance(self._creates, (str, unicode)):
+        if not isinstance(self._creates, str_types):
             raise InvalidTaskDefinition(
                 "each task must define a single `creates` as a string",
                 self.yaml_data,
@@ -123,7 +129,7 @@ def id(self):
     def config_resource_id(self):
         """Canonical way to identify the resource id associated with this Task
         """
-        return 'config:'+self.id
+        return 'config:' + self.id
 
     @property
     def root_directory(self):
@@ -174,7 +180,6 @@ def reset_task_dependencies(self):
         self.downstream_tasks.clear()
 
     def get_all_filenames(self):
-
         """Identify the set of all filenames that pertain to this task
         """
         # TODO: when we allow for non-filesystem targets, this will
@@ -190,11 +195,10 @@ def get_current_state(self):
         # the machinery in self.get_stream_state to calculate the
         # state
         msg = self.creates + str(self.depends) + str(self._command)
-        keys = self.attrs.keys()
-        keys.sort()
+        keys = sorted(self.attrs.keys())
         for k in keys:
             msg += k + str(self.attrs[k])
-        return self.get_stream_state(StringIO.StringIO(msg))
+        return self.get_stream_state(StringIO(msg))
 
     def in_sync(self):
         """Test whether this task is in sync with the stored state and
@@ -242,8 +246,14 @@ def timed_run(self):
 
         # confirm that all depends resources exist on the filesystem
         if not all(resource.exists() for resource in self.depends_resources):
-            raise CommandLineException(self.depends + (
-                " does not exist just before running this task. "
+            unmet = self.depends
+            if isinstance(unmet, list):
+                unmet = '{} and {} do'.format(', '.join(unmet[:-1]),
+                                              unmet[-1])
+            else:
+                unmet = unmet + ' does'
+            raise CommandLineException(unmet + (
+                " not exist just before running this task. "
                 "Double check the `depends` to confirm that these "
                 "dependencies are correct for this task."
             ))
diff --git a/flo/templates/__init__.py b/flo/templates/__init__.py
index 3d45b1b..3be84e6 100644
--- a/flo/templates/__init__.py
+++ b/flo/templates/__init__.py
@@ -9,11 +9,11 @@ def render_from_string(template_string, **context_dict):
     env = jinja2.Environment(undefined=jinja2.StrictUndefined)
     try:
         template_obj = env.from_string(template_string)
-    except jinja2.exceptions.TemplateSyntaxError, error:
+    except jinja2.exceptions.TemplateSyntaxError as error:
         raise JinjaTemplateError(template_string, error)
     try:
         return template_obj.render(**context_dict)
-    except jinja2.exceptions.UndefinedError, error:
+    except jinja2.exceptions.UndefinedError as error:
         raise JinjaRenderError(template_string, error, **context_dict)
 
 
diff --git a/flo/types.py b/flo/types.py
index 081e378..9cabad3 100644
--- a/flo/types.py
+++ b/flo/types.py
@@ -1,4 +1,5 @@
 import collections
+import six
 
 
 class FrozenDict(collections.Mapping):
@@ -21,7 +22,7 @@ def __getitem__(self, key):
         return self._d[key]
 
     def __hash__(self):
-        return hash(tuple(sorted(self._d.iteritems())))
+        return hash(tuple(sorted(six.iteritems(self._d))))
 
 
 class UniqueOrderedList(list):
diff --git a/tests/run_functional_tests.sh b/tests/run_functional_tests.sh
index 5a95f97..2df56f4 100755
--- a/tests/run_functional_tests.sh
+++ b/tests/run_functional_tests.sh
@@ -21,7 +21,7 @@ if [ $? -ne 0 ]; then
 fi
 
 # formatting functions
-red () { 
+red () {
     echo $'\033[31m'"$1"$'\033[0m'
 }
 
@@ -80,20 +80,22 @@ update_status $? "--start-at tests failed"
 # modifying a specific task that would otherwise branch to other tasks
 # and make sure that skipping it does not trigger the workflow to run
 cd ${EXAMPLE_ROOT}/model-correlations
-flo run -f
-sed -i 's/\+1/+2/g' flo.yaml
+flo run --force
+sed 's/\+1/+2/g' flo.yaml > new_flo.yaml
+mv flo.yaml old_flo.yaml
+mv new_flo.yaml flo.yaml
 flo run --skip data/x_y.dat
 grep "No tasks are out of sync" .flo/flo.log > /dev/null
 update_status $? "Nothing should have been run when --skip'ping changed task"
 flo run
 grep "|-> cut " .flo/flo.log > /dev/null
 update_status $? "data/x_y.dat command was not re-run even though it changed"
-sed -i 's/\+2/+1/g' flo.yaml
+mv old_flo.yaml flo.yaml
 cd ${EXAMPLE_ROOT}
 
 # test the --only option
 cd ${EXAMPLE_ROOT}/hello-world
-flo run -f
+flo run --force
 flo run --only data/hello_world.txt
 grep "No tasks are out of sync" .flo/flo.log > /dev/null
 update_status $? "data/hello_world.txt shouldn't have been run"
@@ -111,7 +113,7 @@ flo clean --force
 update_status $? "force cleaning failed on deterministic-order example"
 flo run --force
 update_status $? "deterministic-order example failed somewhere along the way"
-sed -n '/|-> /{g;1!p;};h' .flo/flo.log | sort -C
+sed -n '/|-> /{g;1!p;};h' .flo/flo.log | sort -c
 update_status $? "flo not running in expected deterministic order"
 cd ${EXAMPLE_ROOT}