R loop doesn't work while single command works - r

Question

I am trying to covert many time series xts objects to tibbles, and the for loop I wrote does not work properly, I don't know why.
This does not only happen to this particular task, but other task I perform, I have a list called "code", which contains a list of names for all the xts objects I want to convert from.
code <- c('ABT','BA','CL','ROK')
for (i in code)
{
i <- tk_tbl(i, preserve_index = TRUE, rename_index = "index",
timetk_idx = FALSE, silent = FALSE)
}
What is strange is that, if I use a single one without loop, it works beautifully and convert the xts "ABT" to a tibble "ABT"
ABT <- tk_tbl(ABT, preserve_index = TRUE, rename_index = "index",
timetk_idx = FALSE, silent = FALSE)
The error message for the first code is
Warning: No index to preserve. Object otherwise converted to tibble
successfully.
38: In tk_tbl.data.frame(as.data.frame(data), preserve_index, ... :
Edit:
tk_tabl is a function from the package timetk, and it "Coerce time-series objects to tibble."
And code is a vector containing names.
library(timetk)
code <- c('ABT','BA','CL','ROK')
> dput(head(ROK))
structure(c(8.14062, 8.15625, 8.03125, 7.78125, 7.6875, 7.71875,
8.25, 8.15625, 8.125, 7.90625, 7.71875, 7.75, 8.03125, 8.125,
7.90625, 7.65625, 7.625, 7.65625, 8.1875, 8.125, 7.90625, 7.71875,
7.65625, 7.6875, 109600, 80800, 138400, 151600, 96800, 258800,
0.684505, 0.67928, 0.660992, 0.645316, 0.640091, 0.642704),
class=c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date",
.indexTZ = "UTC", tzone = "UTC", src = "yahoo",
updated = structure(1558826745.23035, class = c("POSIXct","POSIXt")),
index = structure(c(378604800, 378950400, 379036800,
379123200, 379209600, 379296000), tzone = "UTC", tclass = "Date"),
.Dim = c(6L, 6L), .Dimnames = list(NULL, c("ROK.Open", "ROK.High",
"ROK.Low", "ROK.Close", "ROK.Volume", "ROK.Adjusted")))

Answer 1

For me it looks like that you expect <- to do what assign is doing.
I think you get your expected result when you change your loop to:
for (i in code) {
assign(i, tk_tbl(i, preserve_index = TRUE, rename_index = "index", timetk_idx = FALSE, silent = FALSE))
}