How to use the asttokens.LineNumbers function in asttokens

def test_linenumbers(self):
    ln = asttokens.LineNumbers("Hello\nworld\nThis\n\nis\n\na test.\n")
    self.assertEqual(ln.line_to_offset(1, 0), 0)
    self.assertEqual(ln.line_to_offset(1, 5), 5)
    self.assertEqual(ln.line_to_offset(2, 0), 6)
    self.assertEqual(ln.line_to_offset(2, 5), 11)
    self.assertEqual(ln.line_to_offset(3, 0), 12)
    self.assertEqual(ln.line_to_offset(4, 0), 17)
    self.assertEqual(ln.line_to_offset(5, 0), 18)
    self.assertEqual(ln.line_to_offset(6, 0), 21)
    self.assertEqual(ln.line_to_offset(7, 0), 22)
    self.assertEqual(ln.line_to_offset(7, 7), 29)
    self.assertEqual(ln.offset_to_line(0),  (1, 0))
    self.assertEqual(ln.offset_to_line(5),  (1, 5))
    self.assertEqual(ln.offset_to_line(6),  (2, 0))
    self.assertEqual(ln.offset_to_line(11), (2, 5))
    self.assertEqual(ln.offset_to_line(12), (3, 0))
    self.assertEqual(ln.offset_to_line(17), (4, 0))

def compress_source_map(code, pos_map, jump_map, source_id):
    linenos = asttokens.LineNumbers(code)
    compressed_map = f"-1:-1:{source_id}:-;"
    last_pos = [-1, -1, source_id]

    for pc in sorted(pos_map)[1:]:
        current_pos = [-1, -1, source_id]
        if pos_map[pc]:
            current_pos[0] = linenos.line_to_offset(*pos_map[pc][:2])
            current_pos[1] = linenos.line_to_offset(*pos_map[pc][2:])-current_pos[0]

        if pc in jump_map:
            current_pos.append(jump_map[pc])

        for i in range(2, -1, -1):
            if current_pos[i] != last_pos[i]:
                last_pos[i] = current_pos[i]
            elif len(current_pos) == i+1:

def __init__(self, source_text):
    self._text = source_text
    self._line_numbers = LineNumbers(source_text)

    # Tokenize the code.
    self._tokens = list(self._generate_tokens(source_text))

    # Extract the start positions of all tokens, so that we can quickly map positions to tokens.
    self._token_offsets = [tok.startpos for tok in self._tokens]