我想获取pyfiglet，但是当我输入python3 -m pip install pyfiglet时，它只会给我一个错误：'python3' is not recognized as an internal of external command, operable program or batch file.我也尝试使用python而不是python3，但是却出现了一个错误：AttributeError: module 'copy' has no attribute 'deepcopy'
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