5 * the carate is renmaed to `text-size` from `text_unit`
8 - `TextUnit::of_char(c)` ⟹ `TextSize::of(c)`
9 - `TextUnit::of_str(s)` ⟹ `TextSize::of(s)`
10 - `TextUnit::from_usize(size)` ⟹ `TextSize::try_from(size).unwrap_or_else(|| panic!(_))`
11 - `unit.to_usize()` ⟹ `usize::from(size)`
12 - `TextRange::from_to(from, to)` ⟹ `TextRange::new(from, to)`
13 - `TextRange::offset_len(offset, size)` ⟹ `TextRange::from_len(offset, size)`
14 - `range.start()` ⟹ `range.start()`
15 - `range.end()` ⟹ `range.end()`
16 - `range.len()` ⟹ `range.len()`
17 - `range.is_empty()` ⟹ `range.is_empty()`
18 - `a.is_subrange(b)` ⟹ `b.contains_range(a)`
19 - `a.intersection(b)` ⟹ `a.intersect(b)`
20 - `a.extend_to(b)` ⟹ `a.cover(b)`
21 - `range.contains(offset)` ⟹ `range.contains(point)`
22 - `range.contains_inclusive(offset)` ⟹ `range.contains_inclusive(point)`