code: public boolean containsSymbolTerm(Token.Symbol symbol) {
  
          for(Term<FormattedNumber> term : terms) {
              if(!(term instanceof NumberTerm.SymbolTerm)) {
                  continue;
              }
  
              final NumberTerm.SymbolTerm symbolTerm = (NumberTerm.SymbolTerm) term;
              if(symbolTerm.getToken().equals(symbol)) {
                  return true;
              }
          }
  
          return false;
  
      }
docs: 記号用の項の中で、指定した記号を含むかどうか。
  @param symbol
  @return