codeDbGraphFromProjectionCodeList :: [ProjectionCode] -> ([CodeDbId], CodeDbGraph)
codeDbGraphFromProjectionCodeList projectionCodeList = (ids, Map.unions trees)
  where (ids, trees) = unzip $ map codeDbGraphFromProjectionCode $ projectionCodeList
codeDbGraphFromProjectionCodeList :: [ProjectionCode] -> ([CodeDbId], CodeDbGraph)
codeDbGraphFromProjectionCodeList projectionCodeList = (ids, Map.unions trees)
  where (ids, trees) = unzip $ map codeDbGraphFromProjectionCode $ projectionCodeList
codeDbGraphFromProjectionCodeList projectionCodeList = (ids, Map.unions trees)
  where (ids, trees) = unzip $ map codeDbGraphFromProjectionCode $ projectionCodeList