sed, 40 bytes

Result

AC

Duration

814ms

Code [DL]

:a
s/\(T.\{50\}\) /\1T/
s/K /KK/
ta
N
ba

stdin

          T                                       
                                                  
                                                  
   K                                              

stdout

          T                                       
          T                                       
          T                                       
   KKKKKKKT                                       

stderr

strace

11    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc86926110 /* 7 vars */) = 0
12    execve("/bin/cat", ["cat", "-"], 0x56452deb0cf8 /* 7 vars */) = 0
12    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
14    execve("/usr/bin/sed", ["/usr/bin/sed", "-f", "/volume/CODE"], 0x56452fbb0330 /* 7 vars */ <unfinished ...>
13    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
14    <... execve resumed> )            = 0
14    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
11    +++ exited with 0 +++