Is there a general way to traverse and replace the items in a nested sequence of arbitrary depth? Say, for instance, that I want to eliminate all the commas in any strings in some absurd nested ...

'.txt': 'Documents/Text', '.rtf': 'Documents/Text', '.odt': 'Documents/Text', '.xlsx': 'Documents/Spreadsheets', '.csv': ...

In the early days of C, you’d occasionally see someone — probably a former Pascal programmer — write something like this: #define BEGIN { #define END } This would usually initiate complaints about ...