Hello, please can anyone help with this error ? 
ERROR: ParseError at /home/yasmine/yocto/poky/meta-openembedded/meta-gnome/recipes-gnome/yelp/yelp_3.34.0.bb:7: Could not inherit file classes/itstool.bbclass

this is the line 7:
inherit gnomebase itstool autotools-brokensep gsettings gettext gtk-doc features_check mime-xdg