'push a new level on the stack with a style dictionnary containing style:value pairs'

def push(self, style={}):

    _style = {}
    for attr in style:
        if ((attr in self.cmds) and (not (style[attr] in self.cmds[attr]))):
            print ((('WARNING:    ESC/POS    PRINTING:    ignoring    invalid    value:    ' + utfstr(style[attr])) + '    for    style:    ') + utfstr(attr))
        else:
            _style[attr] = self.enforce_type(attr, style[attr])
    self.stack.append(_style)
