AWK - command system () and function ()

I have a file:

AA
 BB
 

This command prints:

$ awk '{ORS=""; printf "%s ", $0 } END {print "\n"}' file
 
 AA BB
 

I want to use these commands, but the function:

The first function:

awk 'function my() { system("echo | awk '{ ORS=""; printf "%s ", $0 } END {print "\n"}' file") } BEGIN { my() }'
 

The second function:

awk 'function my() { system("cat file") } BEGIN { my() }'
 

I want to print the result:

AA BB
 

Thank you for your help.

EDIT:

I want to use system(command) in my() function.

awk  'function my() { system(Here I want to insert proper command) } BEGIN { my() }' -> to print the result:
 
 AA BB
 

It is possible to print the result by nesting awk command?

Thanks for any proposed solution.

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