def set_virtualchain_field(cls, opdata, virtualchain_field, value):
        """
        Set a virtualchain field value.
        Used by implementations that generate extra consensus data at the end of a block
        """
        assert virtualchain_field in RESERVED_KEYS, 'Invalid field name {} (choose from {})'.format(virtualchain_field, ','.join(RESERVED_KEYS))
        opdata[virtualchain_field] = value
def set_virtualchain_field ( cls , opdata , virtualchain_field , value ) : assert virtualchain_field in RESERVED_KEYS , 'Invalid field name {} (choose from {})' . format ( virtualchain_field , ',' . join ( RESERVED_KEYS ) ) opdata [ virtualchain_field ] = value
Set a virtualchain field value.
        Used by implementations that generate extra consensus data at the end of a block