Test instance creation and argument assignment
user
```ruby
require 'spec_helper'

describe EventGirl::Client do
  it 'creates instances with two arguments' do
    expect(described_class.instance_method(:initialize).arity).to eql 2
  end

  it 'sets the api_token' do
    subject = described_class.new(nil, 'abcxyz')
    expect(subject.api_token).to eql 'abcxyz'
  end

  it 'sets the url' do
    subject = described_class.new('http://localhost:3000', nil)
    expect(subject.url).to eql 'http://localhost:3000'
  end
end
```
assistant