--- self =~ string
--- self === string

    ʸ string ȤɽޥåԤޤޥå硢
    ޥå֤Υǥå֤ޤ(Ƭ0)ޥåʤä
    硢뤤 string  nil ξˤ nil 
    ޤ

    Ȥ߹ѿ $~ ˥ޥå˴ؤꤵޤ

    string nil Ǥ String ֥ȤǤʤ
    㳰 TypeError ȯޤ

    ruby 1.7 feature: Regexp#=== ϡ֤ͤޤʸ
    Ǥʤޥåʤ false 򡢥ޥå 
    true ֤ޤ

