code: def compute_report(self, texts, context_size=10):
          
          result = defaultdict(list)
          for text in texts:
              for char, examples in self.find_invalid_chars(text, context_size).items():
                  result[char].extend(examples)
          return result
docs: Compute statistics of invalid characters on given texts.
  
          Parameters
          ----------
          texts: list of str
              The texts to search for invalid characters.
          context_size: int
              How many characters to return as the context.
  
          Returns
          -------
          dict of (char -> list of tuple (index, context))
              Returns a dictionary, where keys are invalid characters.
              Values are lists containign tuples with character indices
              and context strings.