Too many mistakes and too many times to do 2 + 2

you can use e-worm comprehensive script available at https://github.com/eworm-de/routeros-scripts you don't have to code anything

There are dozens of threads on this topic on the forum.
Sorry, but I don't use Telegram and I don't tinker with things I can't test.

you can use e-worm comprehensive script available at https://github.com/eworm-de/routeros-scripts you don't have to code anything

you can use e-worm comprehensive script available at https://github.com/eworm-de/routeros-scripts you don't have to code anything

:global testFunc do={ :put "Called with: $1" }
[$testFunc "One"]
[$testFunc "Two"]
[$testFunc "Three"]

/system script run fantom
Called with: One
Called with: Two
Called with: 
Called with: Three
Called with: 4
Called with: 5
Called with: 6
Called with: 7
Called with: 8
Called with: 9

expected from what you write terminal code

[rex@test] > :global testFunc do={ :put "Called with: $1" }
[rex@test] > [$testFunc "One"]
Called with: One
[rex@test] > [$testFunc "Two"]
Called with: Two
[rex@test] > [$testFunc "Three"]
Called with: Three
[rex@test] >

what you really do wrong on terminal code

[rex@test] > {
{... :global testFunc do={ :put "Called with: $1" }
{... [$testFunc "One"]
{... [$testFunc "Two"]
{... [$testFunc "Three"]
{... }
Called with: One
Called with: Two
Called with: 
Called with: Three
[rex@test] > 
[rex@test] > 

one of the way of correctly do on terminal code

[rex@test] > :global testFunc do={ :return "Called with: $1" }
[rex@test] > {
{... :put [$testFunc "One"]
{... :put [$testFunc "Two"]
{... :put [$testFunc "Three"]
{... }
Called with: One
Called with: Two
Called with: Three
[rex@test] > 

example of global function defined later on terminal code

[rex@test] > :global testFunc "nothing, just for example"
[rex@test] > {
{... :set testFunc do={ :return "Called with: $1" }
{... :put [$testFunc "One"]
{... :put [$testFunc "Two"]
{... :put [$testFunc "Three"]
{... }
Called with: One
Called with: Two
Called with: Three
[rex@test] > 

You are not telling us the truth.
Only that line cannot give that result.
I have already seen errors on the second run, they depend on syntax errors made previously, but if you only show that line, no one can help you... or not?

The three rules for prevent that error are very simple, one mandatory, the other almost, the last one depends:
1) :global should never be created inside any parenthesis or any subscript called inside parenthesis (updated is not the same as created)
2) always use :return <something> at the end of a function, "" suffice, and avoid empty :return for exit prematurely from a function.
if is present something in function like :if (x) do={:return y} else={:return z}, this rule obviously is not applied.
3) do not use "do { }" to completely enclose a script or similar bulls–t.

3) do not use "do { }" to completely enclose a script or similar bulls–t.

I don't understand how the function, the "do" block, can't be wrapped in curly brackets "{}"

:global echo do={
    :put "Called with: $1"
    :return ""
}
[$echo "A"]
[$echo "B"]
[$echo "C"]
[$echo "D"]
[$echo "E"]
[$echo "F"]

:global echo do={
    :return "Called with: $1"
}
:put [$echo "A"]
:put [$echo "B"]
:put [$echo "C"]
:put [$echo "D"]
:put [$echo "E"]
:put [$echo "F"]

wrong coding reveal bug on code

[rex@test-v7] /system/script> export      
# 2025-04-04 17:46:40 by RouterOS 7.16.2
# software id = CHR
#
/system script
add dont-require-permissions=no name=script1 owner=admin policy=\
    ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon source=":glo\
    bal echo do={\r\
    \n    :put \"Called with: \$1\"\r\
    \n    :return \"\"\r\
    \n}\r\
    \n[\$echo \"A\"]\r\
    \n[\$echo \"B\"]\r\
    \n[\$echo \"C\"]\r\
    \n[\$echo \"D\"]\r\
    \n[\$echo \"E\"]\r\
    \n[\$echo \"F\"]\r\
    \n"
[rex@test-v7] /system/script> run script1             
Called with: A
Called with: B
Called with: 
Called with: C
Called with: D
Called with: E
Called with: F

correct coding no bug code

[rex@test-v7] /system/script> export      
# 2025-04-04 17:46:40 by RouterOS 7.16.2
# software id = CHR
#
/system script
add dont-require-permissions=no name=script1 owner=admin \
    policy="ftp,reboot,read,write,policy,test,password,sniff,sen\
    sitive,romon" source=":global echo do={\r\
    \n    :return \"Called with: \$1\"\r\
    \n}\r\
    \n:put [\$echo \"A\"]\r\
    \n:put [\$echo \"B\"]\r\
    \n:put [\$echo \"C\"]\r\
    \n:put [\$echo \"D\"]\r\
    \n:put [\$echo \"E\"]\r\
    \n:put [\$echo \"F\"]\r\
    \n"
[rex@test-v7] /system/script> run script1 
Called with: A
Called with: B
Called with: C
Called with: D
Called with: E
Called with: F
[rex@test-v7] /system/script> 

:local void
:global echo do={
    :put "Called with: $1"
    :return ""
}
:set void [$echo "A"]
:set void [$echo "B"]
:set void [$echo "C"]
:set void [$echo "D"]
:set void [$echo "E"]
:set void [$echo "F"]

terminal output rules code

[rex@test-v7] /system/script> run script1 
Called with: A
Called with: B
Called with: C
Called with: D
Called with: E
Called with: F

A simple check in the function body fixes the problem: :if ([$len $0]!=0) do={ }.

:if ([$len [:nothing]]!=0) do={:put true} else={:put false}

:if ([$len ""]!=0) do={:put true} else={:put false}

:if ([$len "xxx"]!=0) do={:put true} else={:put false}

<also can be here useless return>

[$myFunc]; [$myFunc]

Well, it's a typo, I wrote it quickly. It's clear to a fool that : instead of $. What's the difference? Why find fault with this? The principle and solution are shown.