Name file is not defined python. Is not defined. name entry is not defined. nameerror: name 'x' is not defined — что означает эта ошибка?. name 'std' is not defined.

Name file is not defined python. Is not defined. name entry is not defined. nameerror: name 'x' is not defined — что означает эта ошибка?. name 'std' is not defined.
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