message: Lint cleanup in to_ssa
diff: @@ -4,7 +4,7 @@ from collections import defaultdict
  from cfg import block_map, successors, add_terminators, add_entry, reassemble
  from form_blocks import form_blocks
  -from dom import get_dom, dom_fronts, dom_tree, map_inv
  +from dom import get_dom, dom_fronts, dom_tree
  def def_blocks(blocks):
  @@ -91,7 +91,6 @@ def ssa_rename(blocks, phis, succ, domtree, args):
  return phi_args, phi_dests
  -
  def insert_phis(blocks, phi_args, phi_dests, types):
  for block, instrs in blocks.items():
  for dest, pairs in sorted(phi_args[block].items()):
  @@ -121,7 +120,6 @@ def func_to_ssa(func):
  add_entry(blocks)
  add_terminators(blocks)
  succ = {name: successors(block[-1]) for name, block in blocks.items()}
  - pred = map_inv(succ)
  dom = get_dom(succ, list(blocks.keys())[0])
  df = dom_fronts(dom, succ)
  