back.verilog: remove unused imports. NFC.

diff --git a/nmigen/back/verilog.py b/nmigen/back/verilog.py
index 3c7be2b10aefda5fe16a362ba7469f24ca692c4e..19a91e41dd9fb35883c56b634c4fc91c1343b29b 100644 (file)
--- a/nmigen/back/verilog.py
+++ b/nmigen/back/verilog.py
@@ -1,8 +1,3 @@
-import os
-import re
-import subprocess
-import itertools
-
 from .._yosys import *
 from . import rtlil