module CGI::HtmlExtension

# = checkbox("NAME" => "name", "VALUE" => "value", "CHECKED" => true)
checkbox("name", "value", true)

# = checkbox("NAME" => "name", "VALUE" => "value")
checkbox("name", "value")

# = checkbox("NAME" => "name")
checkbox("name")

Alternatively, the attributes can be specified as a hash.

if true, the CHECKED attribute will be included in the element.
+name+, +value+, and +checked+. +checked+ is a boolean value;
The attributes of the element can be specified as three arguments,

Generate a Checkbox Input element as a string.

def checkbox(name = "", value = nil, checked = nil)
  attributes = if name.kind_of?(String)
                 { "TYPE" => "checkbox", "NAME" => name,
                   "VALUE" => value, "CHECKED" => checked }
               else
                 name["TYPE"] = "checkbox"
                 name
               end
  input(attributes)
end