@make_certifier()<EOL>def certify_bool(value, required=True):
if certify_required(<EOL>value=value,<EOL>required=required,<EOL>):<EOL><INDENT>return<EOL><DEDENT>if not isinstance(value, bool):<EOL><INDENT>raise CertifierTypeError(<EOL>message="<STR_LIT>".format(<EOL>cls=value.__class__.__name__),<EOL>value=value,<EOL>required=required,<EOL>)<EOL><DEDENT>
Certifier for boolean values.

:param value:
    The value to be certified.
:param bool required:
    Whether the value can be `None`.  Defaults to True.
:raises CertifierTypeError:
    The type is invalid