default FunctionalCommandBuilder<T> assertUsage(String usage) {
        return assertUsage(usage, DEFAULT_INVALID_USAGE_MESSAGE);
    }
Asserts that the arguments match the given usage string.

Arguments should be separated by a " " space. Optional arguments are denoted by wrapping the argument name in
square quotes "[ ]"

The default failure message is sent if they didn't provide enough arguments.

@param usage the usage string
@return the builder instance
helper/src/main/java/me/lucko/helper/command/functional/FunctionalCommandBuilder.java