doesn't exist name of numop to look up (vecops are allowed). messages coming out of it are not guaranteed to come out in any particular order. if class or alias is not found in GridFlow's numop database. \$1=1: this is a one-input operator \$1=2: this is a two-input operator \$1=1: this is an operator on plain numbers \$1=2: this is an operator on complex numbers or polar coordinates \$1=1: allowed in [#fold] and [#scan] and as the 'fold' attribute of [#inner] and [#convolve]. \$1=0: not allowed in those circumstances (but still allowed in [#], [#outer], [#draw_polygon], etc) although internally, numops also hold info about neutral elements and absorbent elements, this info is currently unavailable through [gf/numop_info].