code: func (r *RuleDefault) IsSentenceSeparator(rune rune) bool {
  	chr := string(rune)
  
  	for _, val := range r.sentenceSeparators {
  		if chr == val {
  			return true
  		}
  	}
  
  	return false
  }
docs: // IsSentenceSeparator method retrieves true when a character is a kind of
  // special character and possibly it separates to words from each other.