addEmptyEPDomVarDeclToSig :: Sign -> Token -> Sign
addEmptyEPDomVarDeclToSig sig tok = sig {epvars = ev'}
    where ev' = Map.insertWith f tok Nothing $ epvars sig
          f _ v = v
addEmptyEPDomVarDeclToSig :: Sign -> Token -> Sign
addEmptyEPDomVarDeclToSig sig tok = sig {epvars = ev'}
    where ev' = Map.insertWith f tok Nothing $ epvars sig
          f _ v = v
addEmptyEPDomVarDeclToSig sig tok = sig {epvars = ev'}
    where ev' = Map.insertWith f tok Nothing $ epvars sig
          f _ v = v