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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 check_path(path, credentials=None):
 """ Check that specified output path does not already exist The ValueError message will suggest calling with overwrite=True; this function is expected to be called from the various output methods that accept an 'overwrite' keyword argument. """

    from thunder.readers import get_file_reader
    reader = get_file_reader(path)(credentials=credentials)
    existing = reader.list(path, directories=True)
    if existing:
        raise ValueError('Path %s appears to already exist. Specify a new directory, '
                         'or call with overwrite=True to overwrite.' % path)