Examples

        <%= input large,
                  prepend => { radio_button => ['yes'] },
                  input => { text_field => ['username'] },
                  append => '@'
        %>

        <div class="input-group input-group-lg">
            <span class="input-group-addon"><input name="yes" type="radio" /></span>
            <input class="form-control" id="username" type="text" name="username" />
            <span class="input-group-addon">@</span>
        </div>

A `large` input group with a radio button prepended and a string appended.

@

        <%= input input => { text_field => ['username'] },
                  append => { button => ['Click me!'] },
        %>

        <div class="input-group">
            <input class="form-control" id="username" type="text" name="username" />
            <span class="input-group-btn"><button class="btn btn-default" type="button">Click me!</button></span>
        </div>

An input group with a button.