default @SideEffectFree char peek() {
        if (this.cursor() >= this.input().length()) {
            throw new CursorOutOfBoundsException(
                    this.cursor(),
                    this.length()
            );
        }
        return this.input().charAt(this.cursor());
    }
Reads the character at the cursor without moving the cursor.

@return the character at the cursor.
@throws CursorOutOfBoundsException If the cursor has exceeded the input
cloud-core/src/main/java/org/incendo/cloud/context/CommandInput.java