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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def execute_command(self, tab_name, panel_name, command_module, command_class, command_data=None):
 """Append an execute external command entry to the journal. This instructs Revit to execute the provided command from the provided module, tab, and panel. Args: tab_name (str):
 name of ribbon tab that contains the command panel_name (str):
 name of ribbon panel that contains the command command_module (str):
 name of module that provides the command command_class (str):
 name of command class inside command module command_data (dict):
 dict of string data to be passed to command Examples: """

        # make sure command_data is not empty
        command_data = {} if command_data is None else command_data
        # make the canonical name for the command
        cmdclassname = '{}.{}'.format(command_module, command_class)

        self._add_entry(templates.EXTERNAL_COMMAND
                                 .format(external_command_tab=tab_name,
                                         external_command_panel=panel_name,
                                         command_class_name=command_class,
                                         command_class=cmdclassname))

        # count the data
        data_count = len(command_data.keys())

        # create the entry for the command data
        if data_count > 0:
            data_str_list = []
            for k, v in command_data.items():
                data_str_list.append(' "{}" , "{}"'.format(k, v))

            data_str = '_\n    ,'.join(data_str_list)
            self._add_entry(templates.EXTERNAL_COMMANDDATA
                                     .format(data_count=data_count,
                                             data_string=data_str))