[NTG-context] Add arrow tips to axes in lmt_function

Hi, list! I want to know how to add arrow tips for axes (x, y) to a function. I did the following based on a luametafun example: \starttext \startMPcode{doublefun} draw lmt_function [ xmin=0, xmax=10, xstep=.05, ymin=-2, ymax=2, code="1.5 * math.cosd(240 * math.sqrt(x))", xlabels="no",ylabels="no", sx=2mm, sy=4mm, linewidth=.025mm, offset=.1mm,] xsized 8cm; \stopMPcode \stoptext But I didn't find anywhere in manuals or the mailing list concerning arrows, nor key-value pairs for lmt_function. Thank you in advance. Best regards, Jairo :)