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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 lsfiles(root=".", **kwargs):
 """ Return only files from a directory listing. Arguments: root (str):
 Path to directory. Can be relative or absolute. **kwargs: Any additional arguments to be passed to ls(). Returns: list of str: A list of file paths. Raises: OSError: If root directory does not exist. """

    paths = ls(root=root, **kwargs)
    if isfile(root):
        return paths
    return [_path for _path in paths if isfile(path(root, _path))]