# Convert `self` to a human readable String corresponding to `format`.
# TODO document allowed format.
- fun strftime(format: String): String import String.to_cstring, NativeString.to_s `{
+ fun strftime(format: String): String import String.to_cstring, NativeString.to_s_with_copy `{
char* buf, *c_format;
buf = (char*)malloc(100);