Example of pipeline

cleaner.py

from pipeline import pipeline

class Cleaner(object):
    def __init__(self):
        self.pipeline = pipeline

    def add_pipeline(self, p):
        self.pipeline.append(p)

    def __call__(self, s):
        for p in pipeline:
            s = p(s)
        return s

    def __repr__(self):
        return ' '.join([p.__name__ for p in self.pipeline])

if __name__ == '__main__':
    print(pipeline)

    s = 'TEST    me'

    cleaner = Cleaner()
    print(cleaner)

    s = cleaner(s)
    print(s)

pipeline.py

import re

pipeline = []

def registry(func):
    pipeline.append(func)
    return func

@registry
def lowercase(s):
    return s.lower()

@registry
def remove_extra_spaces(s):
    return re.sub('\s+', ' ', s)