def t_surfabu(self, num_frame, xax, t0_model=<NUM_LIT:0>,<EOL>title='<STR_LIT>', t_eps=<NUM_LIT>,<EOL>plot_CO_ratio=False):
if num_frame >= <NUM_LIT:0>:<EOL><INDENT>pyl.figure(num_frame)<EOL><DEDENT>if xax == '<STR_LIT:time>':<EOL><INDENT>xaxisarray = self.get('<STR_LIT>')[t0_model:]<EOL><DEDENT>elif xax == '<STR_LIT>':<EOL><INDENT>xaxisarray = self.get('<STR_LIT>')[t0_model:]<EOL><DEDENT>elif xax == '<STR_LIT>':<EOL><INDENT>xaxisarray = self.get('<STR_LIT>')<EOL>xaxisarray=np.log10(max(xaxisarray[t0_model:])+t_eps-xaxisarray[t0_model:])<EOL><DEDENT>else:<EOL><INDENT>print('<STR_LIT>'+'<STR_LIT>')<EOL><DEDENT>star_mass         = self.get('<STR_LIT>')<EOL>surface_c12       = self.get('<STR_LIT>')<EOL>surface_c13       = self.get('<STR_LIT>')<EOL>surface_n14       = self.get('<STR_LIT>')<EOL>surface_o16       = self.get('<STR_LIT>')<EOL>target_n14 = -<NUM_LIT><EOL>COratio=old_div((surface_c12*<NUM_LIT>),(surface_o16*<NUM_LIT>))<EOL>t0_mod=xaxisarray[t0_model]<EOL>log10_c12=np.log10(surface_c12[t0_model:])<EOL>symbs=['<STR_LIT>','<STR_LIT:->','<STR_LIT>','<STR_LIT>','<STR_LIT>','<STR_LIT:->','<STR_LIT>','<STR_LIT>','<STR_LIT::>','<STR_LIT:->','<STR_LIT>','<STR_LIT>']<EOL>pyl.plot(xaxisarray,log10_c12,symbs[<NUM_LIT:0>],label='<STR_LIT>')<EOL>pyl.plot(xaxisarray,np.log10(surface_c13[t0_model:]),symbs[<NUM_LIT:1>],label='<STR_LIT>')<EOL>pyl.plot(xaxisarray,np.log10(surface_n14[t0_model:]),symbs[<NUM_LIT:2>],label='<STR_LIT>')<EOL>pyl.plot(xaxisarray,np.log10(surface_o16[t0_model:]),symbs[<NUM_LIT:3>],label='<STR_LIT>')<EOL><INDENT>pyl.plot([min(xaxisarray[t0_model:]-t0_mod),max(xaxisarray[t0_model:]-t0_mod)],[target_n14,target_n14])<EOL><DEDENT>pyl.ylabel('<STR_LIT>')<EOL>pyl.legend(loc=<NUM_LIT:2>)<EOL>if xax == '<STR_LIT:time>':<EOL><INDENT>pyl.xlabel('<STR_LIT>')<EOL><DEDENT>elif xax == '<STR_LIT>':<EOL><INDENT>pyl.xlabel('<STR_LIT>')<EOL><DEDENT>elif xax == '<STR_LIT>':<EOL><INDENT>pyl.xlabel('<STR_LIT>')<EOL><DEDENT>if plot_CO_ratio:<EOL><INDENT>pyl.twinx()<EOL>pyl.plot(xaxisarray,COratio[t0_model:],'<STR_LIT>',label='<STR_LIT>')<EOL>pyl.ylabel('<STR_LIT>')<EOL>pyl.legend(loc=<NUM_LIT:4>)<EOL><DEDENT>pyl.title(title)<EOL>if xax == '<STR_LIT>':<EOL><INDENT>self._xlimrev()<EOL><DEDENT>
t_surfabu plots surface abundance evolution as a function of
time.

Parameters
----------
num_frame : integer
    Number of frame to plot this plot into, if <0 don't open
    figure.
xax : string
    Either model, time or logrevtime to indicate what is to be
    used on the x-axis.
t0_model : integer, optional
    Model for the zero point in time, for AGB plots this would
    be usually the model of the 1st TP, which can be found with
    the Kippenhahn plot.  The default is 0.
title : string, optional
    Figure title.  The default is "surface abundance".
t_eps : float, optional
    Time eps at end for logrevtime.  The default is 1.e-3.
plot_CO_ratio : boolean, optional
    On second axis True/False.  The default is False.