class_docstr: The scansion symbols used can be configured by passing a suitable constants class to
  the constructor.
docstr: The third syllable of a hendecasyllabic line is long, so we will convert it.
  
  :param scansion: scansion string
  :return: scansion string with corrected start
  
  >>> print(HendecasyllableScanner().correct_invalid_start(
  ... "- U U  U U  - U   -  U - U").strip())
  - U -  U U  - U   -  U - U
docstr_tok: ["The","third","syllable","of","a","hendecasyllabic","line","is","long",",","so","we","will","convert","it",".",":","param","scansion",":","scansion","string",":","return",":","scansion","string","with","corrected","start",">",">",">","print","(","HendecasyllableScanner","(",")",".correct_invalid_start","(","...","``","-","U","U","U","U","-","U","-","U","-","U","''",")",".strip","(",")",")","-","U","-","U","U","-","U","-","U","-","U"]
code: def correct_invalid_start(self, scansion: str) -> str:
      """
      The third syllable of a hendecasyllabic line is long, so we will convert it.
  
      :param scansion: scansion string
      :return: scansion string with corrected start
  
      >>> print(HendecasyllableScanner().correct_invalid_start(
      ... "- U U  U U  - U   -  U - U").strip())
      - U -  U U  - U   -  U - U
      """
      mark_list = string_utils.mark_list(scansion)
      vals = list(scansion.replace(" ", ""))
      corrected = vals[:2] + [self.constants.STRESSED] + vals[3:]
      new_line = list(" " * len(scansion))
      for idx, car in enumerate(corrected):
          new_line[mark_list[idx]] = car
      return "".join(new_line)
  
file_path: cltk/src/cltk/prosody/lat/hendecasyllable_scanner.py
imports: import re
  import cltk.prosody.lat.string_utils
  from cltk.prosody.lat.metrical_validator import MetricalValidator
  from cltk.prosody.lat.scansion_constants import ScansionConstants
  from cltk.prosody.lat.scansion_formatter import ScansionFormatter
  from cltk.prosody.lat.syllabifier import Syllabifier
  from cltk.prosody.lat.verse import Verse
  from cltk.prosody.lat.verse_scanner import VerseScanner
label_desc: Use image node_id 3 for calling the HendecasyllableScanner obj's underlying member method code with example usage: obj.correct_invalid_start(scansion) and returns: str