default long readLong() {
        return Long.parseLong(this.readString());
    }
Reads the {@link #readString() string until the next whitespace} and parses
in into a {@link Long}.

@return the parsed long
@throws NumberFormatException If the string cannot be parsed into a {@link Long}.
cloud-core/src/main/java/org/incendo/cloud/context/CommandInput.java