constructor(flags, description) {
    this.flags = flags;
    this.required = flags.includes('<'); // A value must be supplied when the option is specified.
    this.optional = flags.includes('['); // A value is optional when the option is specified.
    // variadic test ignores <value,...> et al which might be used to describe custom splitting of single argument
    this.variadic = /\w\.\.\.[>\]]$/.test(flags); // The option can take multiple values.
    this.mandatory = false; // The option must have a value after parsing, which usually means it must be specified on command line.
    const optionFlags = _parseOptionFlags(flags);
    this.short = optionFlags.shortFlag;
    this.long = optionFlags.longFlag;
    this.negate = false;
    if (this.long) {
      this.negate = this.long.startsWith('--no-');
    }
    this.description = description || '';
    this.defaultValue = undefined;
  }
Initialize a new `Option` with the given `flags` and `description`.

@param {string} flags
@param {string} description
@api public