```ruby
$:.unshift File.expand_path("../lib", __FILE__)
require "mustermann/version"

Gem::Specification.new do |s|
  s.name                  = "mustermann"
  s.version               = Mustermann::VERSION
  s.authors               = ["Konstantin Haase", "Zachary Scott"]
  s.email                 = "sinatrarb@googlegroups.com"
  s.homepage              = "https://github.com/sinatra/mustermann"
  s.summary               = %q{Your personal string matching expert.}
  s.description           = %q{A library implementing patterns that behave like regular expressions.}
  s.license               = 'MIT'
  s.required_ruby_version = '>= 2.2.0'
  s.files                 = `git ls-files`.split("\n")
  s.test_files            = `git ls-files -- {test,spec,features}/*`.split("\n")
  s.executables           = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
end
```

Add runtime dependency to ruby2_keywords
user
```ruby
$:.unshift File.expand_path("../lib", __FILE__)
require "mustermann/version"

Gem::Specification.new do |s|
  s.name                  = "mustermann"
  s.version               = Mustermann::VERSION
  s.authors               = ["Konstantin Haase", "Zachary Scott"]
  s.email                 = "sinatrarb@googlegroups.com"
  s.homepage              = "https://github.com/sinatra/mustermann"
  s.summary               = %q{Your personal string matching expert.}
  s.description           = %q{A library implementing patterns that behave like regular expressions.}
  s.license               = 'MIT'
  s.required_ruby_version = '>= 2.2.0'
  s.files                 = `git ls-files`.split("\n")
  s.test_files            = `git ls-files -- {test,spec,features}/*`.split("\n")
  s.executables           = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }

  s.add_runtime_dependency('ruby2_keywords', '~> 0.0.1')
end
```
assistant