@@ -5,17 +5,19 @@
 )
 from paths_cli.compiling.root_compiler import compiler_for
 
+
 def _strategy_name(class_name):
     return f"openpathsampling.strategies.{class_name}"
 
+
 def _group_parameter(group_name):
     return Parameter('group', str, default=group_name,
                      description="the group name for these movers")
 
+
 # TODO: maybe this moves into shooting once we have the metadata?
 SP_SELECTOR_PARAMETER = Parameter('selector', shooting_selector_compiler,
                                   default=None)
-
 ENGINE_PARAMETER = Parameter('engine', compiler_for('engine'),
                              description="the engine for moves of this "
                              "type")
@@ -39,6 +41,7 @@ def _group_parameter(group_name):
     name='one-way-shooting',
 )
 build_one_way_shooting_strategy = ONE_WAY_SHOOTING_STRATEGY_PLUGIN
+
 # build_two_way_shooting_strategy = StrategyCompilerPlugin(
 #     builder=Builder(_strategy_name("TwoWayShootingStrategy")),
 #     parameters = [
 
@@ -1,5 +1,6 @@
 import numpy as np
-from .errors import InputError
+from paths_cli.compiling.errors import InputError
+
 
 def custom_eval(obj, named_objs=None):
     """Parse user input to allow simple math.
@@ -19,10 +20,12 @@ def custom_eval(obj, named_objs=None):
     }
     return eval(string, namespace)
 
+
 def custom_eval_int(obj, named_objs=None):
     val = custom_eval(obj, named_objs)
     return int(val)
 
+
 def custom_eval_int_strict_pos(obj, named_objs=None):
     val = custom_eval_int(obj, named_objs)
     if val <= 0:
@@ -33,6 +36,7 @@ def custom_eval_int_strict_pos(obj, named_objs=None):
 class UnknownAtomsError(RuntimeError):
     pass
 
+
 def mdtraj_parse_atomlist(inp_str, n_atoms, topology=None):
     """
     n_atoms: int
@@ -47,7 +51,7 @@ def mdtraj_parse_atomlist(inp_str, n_atoms, topology=None):
         raise TypeError("Input is not integers")
     if arr.shape != (1, n_atoms):
         # try to clean it up
-        if len(arr.shape) == 1 and arr.shape[0] ==  n_atoms:
+        if len(arr.shape) == 1 and arr.shape[0] == n_atoms:
             arr.shape = (1, n_atoms)
         else:
             raise TypeError(f"Invalid input. Requires {n_atoms} "
 
@@ -1,13 +1,16 @@
 import os
-from .errors import InputError
+from paths_cli.compiling.errors import InputError
 from paths_cli.compiling.root_compiler import compiler_for
 
+
 def get_topology_from_engine(dct):
     """If given the name of an engine, use that engine's topology"""
     engine_compiler = compiler_for('engine')
     if dct in engine_compiler.named_objs:
         engine = engine_compiler.named_objs[dct]
         return getattr(engine, 'topology', None)
+    return None
+
 
 def get_topology_from_file(dct):
     """If given the name of a file, use that to create the topology"""
@@ -16,6 +19,7 @@ def get_topology_from_file(dct):
         import openpathsampling as paths
         trj = md.load(dct)
         return paths.engines.MDTrajTopology(trj.topology)
+    return None
 
 
 class MultiStrategyBuilder:
@@ -35,6 +39,7 @@ def __call__(self, dct):
         # only get here if we failed
         raise InputError.invalid_input(dct, self.label)
 
+
 build_topology = MultiStrategyBuilder(
     [get_topology_from_file, get_topology_from_engine],
     label='topology',
 
@@ -1,11 +1,12 @@
 import operator
 import functools
 
-from .core import Parameter
-from .tools import custom_eval
+from paths_cli.compiling.core import Parameter
+from paths_cli.compiling.tools import custom_eval
 from paths_cli.compiling.plugins import VolumeCompilerPlugin, CategoryPlugin
 from paths_cli.compiling.root_compiler import compiler_for
 
+
 # TODO: extra function for volumes should not be necessary as of OPS 2.0
 def cv_volume_build_func(**dct):
     import openpathsampling as paths
@@ -18,6 +19,7 @@ def cv_volume_build_func(**dct):
     # TODO: wrap this with some logging
     return builder(**dct)
 
+
 CV_VOLUME_PLUGIN = VolumeCompilerPlugin(
     builder=cv_volume_build_func,
     parameters=[
@@ -39,6 +41,7 @@ def cv_volume_build_func(**dct):
     'items': {"$ref": "#/definitions/volume_type"}
 }
 
+
 INTERSECTION_VOLUME_PLUGIN = VolumeCompilerPlugin(
     builder=lambda subvolumes: functools.reduce(operator.__and__,
                                                 subvolumes),
@@ -52,6 +55,7 @@ def cv_volume_build_func(**dct):
 
 build_intersection_volume = INTERSECTION_VOLUME_PLUGIN
 
+
 UNION_VOLUME_PLUGIN = VolumeCompilerPlugin(
     builder=lambda subvolumes: functools.reduce(operator.__or__,
                                                 subvolumes),
@@ -65,5 +69,6 @@ def cv_volume_build_func(**dct):
 
 build_union_volume = UNION_VOLUME_PLUGIN
 
+
 VOLUME_COMPILER = CategoryPlugin(VolumeCompilerPlugin, aliases=['state',
                                                                 'states'])