for file in files:
    sentences=open(file).readlines();
    for sentence in sentences:
        if sentence.startswith(...):
            for k2 in keywords2:
                func(sentence,k2)


func(sentence,k2):

    gs_list=[]                       #####
    for k in keywords:               #####
        if k in sentence:            #####
            gs_list.append(k)        #####

    for k in gs_list:
        do some matching

for file in files:
    sentences=open(file).readlines();
    for sentence in sentences:
        if sentence.startswith(...):

            gs_list=[]                      #####
            for k in keywords:              #####
                if k in sentence:           #####
                    gs_list.append(k)       #####

            for k2 in keywords2:
                func(sentence,k2)



func(sentence,k2):
    for gs in gs_list:
        do some matching