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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 _absolute_path(path, relative_to=None):
    '''
    Return an absolute path. In case ``relative_to`` is passed and ``path`` is
    not an absolute path, we try to prepend ``relative_to`` to ``path``and if
    that path exists, return that one
    '''

    if path and os.path.isabs(path):
        return path
    if path and relative_to is not None:
        _abspath = os.path.join(relative_to, path)
        if os.path.isfile(_abspath):
            log.debug(
                'Relative path \'%s\' converted to existing absolute path '
                '\'%s\'', path, _abspath
            )
            return _abspath
    return path