```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'call_sign/version'

Gem::Specification.new do |spec|
  spec.name          = 'call_sign'
  spec.version       = CallSign::VERSION
  spec.authors       = ['Kevin Elliott']
  spec.email         = ['kevin@welikeinc.com']
  spec.summary       = %q{Handle and process ITU Call Signs}
  spec.description   = %q{Handle and process ITU Call Signs}
  spec.homepage      = 'http://github.com/kevinelliott/call_sign'
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ['lib']

  spec.add_dependency 'countries'

  spec.add_development_dependency 'bundler', '~> 1.5'
  spec.add_development_dependency 'rake'
end
```

Update bundler requirement from ~> 1.5 to ~> 2.0
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'call_sign/version'

Gem::Specification.new do |spec|
  spec.name          = 'call_sign'
  spec.version       = CallSign::VERSION
  spec.authors       = ['Kevin Elliott']
  spec.email         = ['kevin@welikeinc.com']
  spec.summary       = %q{Handle and process ITU Call Signs}
  spec.description   = %q{Handle and process ITU Call Signs}
  spec.homepage      = 'http://github.com/kevinelliott/call_sign'
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ['lib']

  spec.add_dependency 'countries'

  spec.add_development_dependency 'bundler', '~> 2.0'
  spec.add_development_dependency 'rake'
end
```
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