--- method_defined?(name)

    ⥸塼˥󥹥󥹥᥽å name ƤȤ
    ֤ޤname  Symbol ʸǤ

    Module#public_method_defined? [Module/public_method_defined?],
    Module#private_method_defined? [Module/private_method_defined?],
    Module#protected_method_defined? [Module/protected_method_defined?]
    ⻲ȤƤ

