constructor(prefix, state) {
        super()

        this.prefix = prefix
        this.state = state
    }
@param {string} prefix - A prefix text to be inserted.
@param {object} state - A state object.
@param {string} state.lastPrefix - The last prefix which is printed.
@param {boolean} state.lastIsLinebreak -The flag to check whether the last output is a line break or not.