I want to remap `<C-i>*character*` to `i*character*<Esc>` for easy inserting of single characters. This is what I've written:

```
let printable_characters = [ '!', '"', '#', '$', '%', '&', '''', '(', ')', '*', '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', '\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~']
for val in printable_characters
    silent! execute "nnoremap <C-i>" . val . " i" . val . "<Esc>"
    silent! execute "nnoremap <C-a>" . val . " a" . val . "<Esc>"
    unlet val
endfor

```

When I try to source it by executing `:source %`, the following happens:

1. It will complain about how I forgot the `endfor`
2. Once I press return, the file will look like this:

```
let printable_characters = [ '!', '"', '#', '$', '%', '&', '''', '(',          ')', '*', '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', '\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~']
for val in printable_characters
    silent! execute "nnoremap <C-i>" . val . " i" . val . "<Esc>"
    silent! execute "nnoremap <C-a>" . val . " a" . val . "<Esc>"
    unlet val
    silent! execute "nnoremap <C-a>" . val . " a" . val . "<Esc>"
    unlet val
    endfor
endfor

```