fix bug where multiple utility code dependencies could be ignored due to loop variable reassignment (only last one wins)

use tuple instead of list for f-string joining because it is faster to allocate - speedup can be up to 20%

we actually know that FormattedValueNode always returns a Unicode string and no other object type => set node type accordingly

we actually know that FormattedValueNode always returns a Unicode string and no other object type => set node type accordingly