@verb #9253:":add_edge" this none this rxdo #7165
@program #9253:":add_edge" this none this
set_task_perms(caller_perms())
{e} = args
{from, to} = e
from in this.vertices || raise(E_INVARG)
to in this.vertices || raise(E_INVARG)
e in this.edges && raise(E_INVARG)
this.edges = {@this.edges, e}
"Last modified by manta (#7165) on Thu Nov  1 13:41:29 2001 MST."
.