###Internal`CopyListStructure
Internal`CopyListStructure
Examples:
orig = {{{}, {Exp[1]}, 3, {{{{a}}}, c}}}; Internal`CopyListStructure[orig, Range[4]] {{{}, {1}, 2, {{{{3}}}, 4}}}
list = {{{2, 3}, {2, 4}}, {{{3, 4}}}, {{5, 6}, {7, 8}}}; list1 = Flatten[list, 1]; list1[[1]] = {2, 8}; Internal`CopyListStructure[list, Flatten@list1] {{{2, 8}, {2, 4}}, {{{3, 4}}}, {{5, 6}, {7, 8}}}