code: public BetweenCondition between(String low, String high) {
          return new BetweenCondition(this,
                  new LiteralOperand(low),
                  new LiteralOperand(high));
      }
docs: Returns a <code>BetweenCondition</code> that represents a <a href=
  "http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html#ConditionExpressionReference.Comparators"
  >BETWEEN comparison</a> (that evaluates to true if the value of the
  current attribute is greater than or equal to the given low value, and
  less than or equal to the given high value) for building condition
  expression.