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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 get_plaintext_citations(file):
 """ Parse a plaintext file to get a clean list of plaintext citations. The \ file should have one citation per line. :param file: Either the path to the plaintext file or the content of a \ plaintext file. :returns: A list of cleaned plaintext citations. """

    # Handle path or content
    if os.path.isfile(file):
        with open(file, 'r') as fh:
            content = fh.readlines()
    else:
        content = file.splitlines()
    # Clean every line to have plaintext
    cleaned_citations = [tools.clean_whitespaces(line) for line in content]
    return cleaned_citations