Machine name form element should allow prefix and suffix

I think #machine_name form element should allow user/develoepr to set prefix and suffix for the resulting name.
For exmaple if the value of the source is 'This is test' then the resulting machine name would be 'this_is_test'.
If I'd add prefix 'so' then the resulting machine name would be 'so_this_is_test'. If I'd add 'yo' suffix then the resulting machine name would be 'so_this_is_test_yo'. If however 'so_this_is_test_yo' would already exist then the new unique name would be 'so_this_is_test1_yo' and NOT 'so_this_is_test_yo1' since the prefix and sufix values should be preserved.