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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 _find_file(filename):
 """ Find the file path, first checking if it exists and then looking in the data directory """

    import os
    if os.path.exists(filename):
        path = filename
    else:
        path = os.path.dirname(__file__)
        path = os.path.join(path, 'data', filename)

    if not os.path.exists(path):
        raise ValueError("cannot locate file '%s'" %filename)

    return path