def open_r(self, file):
        if not self.steps:
            return open(file, 'r')
        if self.steps[-1][1] == SINK:
            raise ValueError, \
                  'Template.open_r: pipeline ends width SINK'
        cmd = self.makepipeline(file, '')
        return os.popen(cmd, 'r')
t.open_r(file) and t.open_w(file) implement
dataset/ETHPy150Open azoft-dev-team/imagrium/env/Lib/pipes.py/Template.open_r