Where is __go_surface__.m

[Henry F. Mollet]

 [~] -bash-2.05b 501$
'/Applications/Octave.app/Contents/Resources/bin/octave'
GNU Octave, version 2.9.14

peaks.m or sombrero.m use mesh.m and both work.

Lines 67-71 in mesh.m are
## make a default line object, and make it the current axes for the
  ## current figure.
  ca = gca ();

  tmp = __go_surface__ (ca, "xdata", x, "ydata", y, "zdata", z);


But I cannot find __go_surface__.m in the plot directory nor can I locate it
elsewhere !? Why/how does mesh.m work?

[~/documents/cando2] -bash-2.05b 512$ locate __go_surface__.m
[~/documents/cando2] -bash-2.05b 513$

I can locate a similarly named m file:
[~/documents/cando2] -bash-2.05b 511$ locate __go_draw_figure__.m
/Applications/Octave.app/Contents/Resources/share/octave/2.9.14/m/plot/__go_
draw_figure__.m

Henry