SwiftPM ArgumentParser usage

OptionParser.swift

let parser = ArgumentParser(commandName: "swiftfmt", usage: "swiftfmt filename [options]", overview: "Format Swift source code")
let filenameArgument = parser.add(positional: "filename", kind: String.self)
let configrationOption = parser.add(option: "--configuration", kind: String.self)
let versionOption = parser.add(option: "--version", kind: Bool.self)
let verboseOption = parser.add(option: "--verbose", kind: Bool.self, usage: "Show more debugging information")

let result = try parser.parse(Array(CommandLine.arguments.dropFirst()))

if let version = result.get(versionOption) {
    print("Swiftfmt 0.1.0")
    return
}

guard let filename = result.get(filenameArgument) else {
    return print("No input files.")
}
if let configration = result.get(configrationOption) {
    option.configration = configration
}
if let verbose = result.get(verboseOption) {
    option.verbose = verbose
}