About using wordpress esc_html__.

Hello, using the esc_html__ function was tiring to write text domain all the time: D so I created a function as below.

The problem is I can get the following word but it doesn’t save to .pot file. If I make a direct definition of esc_html__ in the function, it works but when I use variables for dynamics, what is the reason?

// Working
function lsph_lang(){
return esc_html__( “Hello”, ‘lsph’ );
}
lsph_lang();

// Not working.
function lsph_lang( $str ){
return esc_html__( $str, ‘lsph’ );
}
lsph_lang( “hello” );