Update ispowerof2.en.md

subjects/ispowerof2.en.md

@@ -8,7 +8,7 @@ This program must print `true` if the given number is a power of 2, otherwise it
 
 -   If there is more than one or no argument the program should print a newline ("`\n`").
 
--   Error cases have to be handled.
+-   When there is only 1 argument, it will always be a positive valid int.
 
 ### Usage :
 
@@ -24,7 +24,5 @@ student@ubuntu:~/ispowerof2$ ./ispowerof2
 
 student@ubuntu:~/ispowerof2$ ./ispowerof2 64 1024
 
-student@ubuntu:~/ispowerof2$ ./ispowerof2 notanumber | cat -e
-strconv.Atoi: parsing "a": invalid syntax$
 student@ubuntu:~/ispowerof2$
 ```