'Validate the format for the type converters and then copy those
which are valid converters for this column (i.e. converter type is
a subclass of col.type)'

@staticmethod
def _validate_and_copy(col, converters):

    converters_out = []
    try:
        for converter in converters:
            (converter_func, converter_type) = converter
            if (not issubclass(converter_type, NoType)):
                raise ValueError()
            if issubclass(converter_type, col.type):
                converters_out.append((converter_func, converter_type))
    except (ValueError, TypeError):
        raise ValueError('Error:    invalid    format    for    converters,    see    documentation\n{}'.format(converters))
    return converters_out
