add docstrings to Signals class
add docstrings to Signals class

bk2204/urwid,mountainstorm/urwid,tonycpsu/urwid,harlowja/urwid,hkoof/urwid,inducer/urwid,rndusr/urwid,ivanov/urwid,westurner/urwid,zyga/urwid,wardi/urwid,foreni-packages/urwid,mountainstorm/urwid,drestebon/urwid,westurner/urwid,bk2204/urwid,wardi/urwid,tonycpsu/urwid,foreni-packages/urwid,rndusr/urwid,drestebon/urwid,westurner/urwid,harlowja/urwid,rndusr/urwid,harlowja/urwid,inducer/urwid,hkoof/urwid,bk2204/urwid,zyga/urwid,ivanov/urwid,ivanov/urwid,inducer/urwid,foreni-packages/urwid,urwid/urwid,Julian/urwid,Julian/urwid,urwid/urwid,Julian/urwid,wardi/urwid,urwid/urwid,zyga/urwid,douglas-larocca/urwid,drestebon/urwid,hkoof/urwid,douglas-larocca/urwid,tonycpsu/urwid,mountainstorm/urwid,douglas-larocca/urwid