<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_field(self, key, field):
 """ Adds a field to the dialog with a unique identifier. Note: You can access to the fields content calling the function GenericDialog.get_field(key). Args: key (str):
 The unique identifier for the field. field (Widget):
 The widget to be added to the dialog, TextInput or any Widget for example. """

        self.inputs[key] = field
        container = HBox()
        container.style.update({'justify-content':'space-between', 'overflow':'auto', 'padding':'3px'})
        container.append(self.inputs[key], key=key)
        self.container.append(container, key=key)