stop if input does not exist
stop if input does not exist

fboehm/labnotebook,fboehm/cboettig_site,fboehm/cboettig_site,fboehm/labnotebook,fboehm/cboettig_site,antass/labnotebook3,fboehm/cboettig_site,fboehm/labnotebook,fboehm/cboettig_site,antass/labnotebook3,fboehm/labnotebook,antass/labnotebook3,fboehm/labnotebook,fboehm/labnotebook