code: public int hash(String symbol) {
  
          int code = 0;
          int length = symbol.length();
          for (int i = 0; i < length; i++) {
              code = code * 37 + symbol.charAt(i);
          }
          return code & 0x7FFFFFF;
  
      }
docs: Returns a hashcode value for the specified symbol. The value
  returned by this method must be identical to the value returned
  by the <code>hash(char[],int,int)</code> method when called
  with the character array that comprises the symbol string.
  
  @param symbol The symbol to hash.