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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 create_prompt(prompt):
 """Create a prompt manager. Parameters prompt : str or class driving from BasePromptManager The prompt name ('python' or 'ipython') or a custom PromptManager class. """

    if prompt is None:
        prompt = 'python'
    if prompt == 'python':
        prompt = PythonPromptManager
    elif prompt == 'ipython':
        prompt = IPythonPromptManager
    # Instanciate the class.
    if isinstance(prompt, BasePromptManager):
        return prompt
    else:
        return prompt()