code: def _exclude_pattern(self, pattern, anchor=True, prefix=None,
                           is_regex=False):
          
          found = False
          pattern_re = self._translate_pattern(pattern, anchor, prefix, is_regex)
          for f in list(self.files):
              if pattern_re.search(f):
                  self.files.remove(f)
                  found = True
          return found
docs: Remove strings (presumably filenames) from 'files' that match
          'pattern'.
  
          Other parameters are the same as for 'include_pattern()', above.
          The list 'self.files' is modified in place. Return True if files are
          found.
  
          This API is public to allow e.g. exclusion of SCM subdirs, e.g. when
          packaging source distributions