docs: def _get_char_offsets(self, char_offsets):
          """Store or calculate char_offsets, adding the offset of the doc end"""
          if char_offsets:
              char_offsets = char_offsets
              char_offsets.append(len(self.text))
          else:
              char_offsets = np.zeros(len(self.tokens) + 1)
              for i, tok in enumerate(self.tokens):
                  # Add 1 to account for the spaces between tokens
                  char_offsets[i + 1] = char_offsets[i] + len(tok) + 1
              char_offsets[-1] = len(self.text)
          return np.array(char_offsets)