15.0.3 `glib_line'
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glib_line(X0,Y0,X1,Y1)
     :   It draws the line [X0,Y0]- [X1,Y1] with COLOR

glib_line(X0,Y0,X1,Y1 | COLOR=key0)
     : This function allows optional variables   COLOR
Example:
      glib_line(0,0,5,3/2 | color=0xff00ff);

