--- /dev/null
+/^\s*unimplemented!()$/ { # if the current line is an "unimplemented!()"
+ : isunimp
+ N; # load next line
+ /\n\s*unimplemented!()$/ { # see if that one is also "unimplemented!()"
+ D; # delete first line, keep all the rest
+ b isunimp
+ }
+}