'Check whether the instance conforms to the given format.
:argument instance: the instance to check
:type: any primitive type (str, number, bool)
:argument str format: the format that instance should conform to
:raises: :exc:`FormatError` if instance does not conform to format'

def check(self, instance, format):

    if (format not in self.checkers):
        return
    (func, raises) = self.checkers[format]
    (result, cause) = (None, None)
    try:
        result = func(instance)
    except raises as e:
        cause = e
    if (not result):
        raise FormatError(('%r    is    not    a    %r' % (instance, format)), cause=cause)
