By wrapping the content of the script in '{', '}', sh will not start
executing any commands until the closing '}' is encountered.
Proof:
$ cat test1.sh
echo hello world
MISSING STUFF
$ sh test1.sh
hello world
test1.sh: line 2: MISSING: command not found
$ cat test2.sh
{
echo hello world
MISSING STUFF
$ sh test2.sh
test2.sh: line 4: syntax error: unexpected end of file
By wrapping the content of the script in '{', '}', sh will not start executing any commands until the closing '}' is encountered.
Proof: