-- Return the non-'?' part of a mvars string.
mv2String :: Nom -> String
mv2String nm = case name2String nm of
  '?':suffix -> suffix
  _          -> error $ "mv2String: not an mvar: " ++ show nm
mv2String :: Nom -> String
mv2String nm = case name2String nm of
  '?':suffix -> suffix
  _          -> error $ "mv2String: not an mvar: " ++ show nm
mv2String nm = case name2String nm of
  '?':suffix -> suffix
  _          -> error $ "mv2String: not an mvar: " ++ show nm