Fix iter3() error on Python 3.7 and pass flake8
Fix iter3() error on Python 3.7 and pass flake8

talha131/pelican-plugins,talha131/pelican-plugins,xsteadfastx/pelican-plugins,mortada/pelican-plugins,mikitex70/pelican-plugins,talha131/pelican-plugins,MarkusH/pelican-plugins,xsteadfastx/pelican-plugins,talha131/pelican-plugins,mortada/pelican-plugins,mortada/pelican-plugins,MarkusH/pelican-plugins,MarkusH/pelican-plugins,rlaboiss/pelican-plugins,mortada/pelican-plugins,mikitex70/pelican-plugins,MarkusH/pelican-plugins,rlaboiss/pelican-plugins,xsteadfastx/pelican-plugins,mortada/pelican-plugins,mikitex70/pelican-plugins,rlaboiss/pelican-plugins,mikitex70/pelican-plugins,talha131/pelican-plugins,xsteadfastx/pelican-plugins,MarkusH/pelican-plugins,rlaboiss/pelican-plugins