sources can be file name or code:
        sources=['x.c','int main(){}']
        or
        sources='int main(){}'

def build(self, sources=None, headers=None):
        ''' sources can be file name or code:
        sources=['x.c','int main(){}']
        or
        sources='int main(){}'
        '''
        tempdir = None
        strings, files = separate_sources(sources)
        if len(strings) or headers:
            # TODO: remove tempdir
            tempdir = tmpdir()

        temp_list = [tmpfile(x, tempdir, '.c') for x in strings]

        if headers:
            for n, s in headers.items():
                (Path(tempdir) / n).write_text(s)

        cmd = self.command_list(files + temp_list)
        if tempdir:
            cmd += ['-I' + tempdir]
        self.proc = Proc(cmd).call()
#        for x in temp_list:
#            os.remove(x)

        if not self.ok:
            raise AvrGccCompileError(cmd, sources, self.error_text)