Fix lint

neurom/features/neurite.py

@@ -55,7 +55,6 @@
 from neurom.features import NameSpace, feature, bifurcation as bf, section as sf
 from neurom.geom import convex_hull
 from neurom.morphmath import interval_lengths
-from neurom.utils import flatten
 from neurom.core.types import tree_type_checker as is_type
 
 feature = partial(feature, namespace=NameSpace.NEURITE)
@@ -84,7 +83,6 @@ def homogeneous_filter(section):
 @feature(shape=())
 def max_radial_distance(neurite, origin=None, section_type=NeuriteType.all):
     """Get the maximum radial distances of the termination sections."""
-
     term_radial_distances = section_term_radial_distances(
         neurite, origin=origin, section_type=section_type
     )