human
Solve the following python programming problem given the following code:
def _add_c_module(dist, ffi, module_name, source, source_extension, kwds) : 
    from distutils.core import Extension 
    from distutils.command.build_ext import build_ext 
    from distutils.dir_util import mkpath 
    from distutils import log 
    from cffi import recompiler 
    allsources = ['$PLACEHOLDER'] 
    allsources.extend (kwds.pop ('sources', [])) 
    ext = Extension (name = module_name, sources = allsources, ** kwds) 
    def make_mod(tmpdir, pre_run = None) : 
        c_file = os.path.join (tmpdir, (module_name + source_extension)) 
        log.info (('generating cffi module %r' % c_file)) 
        mkpath (tmpdir) 
        if (pre_run is not None) : 
            pre_run (ext, ffi) 
updated = recompiler.make_c_source (ffi, module_name, source, c_file) 
        if (not updated) : 
            log.info ('already up-to-date') 
return c_file 
if (dist.ext_modules is None) : 
        dist.ext_modules = [] 
dist.ext_modules.append (source) 
    base_class = dist.cmdclass.get ('build_ext', build_ext) 
    class build_ext_make_mod (base_class) : 
        def run(self) : 
            if (ext.sources [0] == '$PLACEHOLDER') : 
                pre_run = getattr (self, 'pre_run', None) 
                ext.sources [0] = make_mod (self.build_temp, pre_run) 
base_class.run (self) 
dist.cmdclass ['build_ext'] = build_ext_make_mod 

    
    

    Fix the buggy line: dist.ext_modules.append (source)
assistant
#Here is Python program to fix the buggy line: dist.

dist.ext_modules.append (ext)