{,_}tools→{,_}utils

In context of nMigen, "tools" means "parts of toolchain", so it is
confusing to have a completely unrelated module also called "tools".

nmigen/back/pysim.py

@@ -6,7 +6,7 @@ from bitarray import bitarray
 from vcd import VCDWriter
 from vcd.gtkw import GTKWSave
 
-from .._tools import flatten
+from .._utils import flatten
 from ..hdl.ast import *
 from ..hdl.ir import *
 from ..hdl.xfrm import ValueVisitor, StatementVisitor

nmigen/back/rtlil.py

@@ -3,7 +3,7 @@ import textwrap
 from collections import defaultdict, OrderedDict
 from contextlib import contextmanager
 
-from .._tools import bits_for, flatten
+from .._utils import bits_for, flatten
 from ..hdl import ast, rec, ir, mem, xfrm