(Python) Keeping the Last N items

lastN.py

from collections import deque

def search(lines, pattern, history=5):
    previous_lines = deque(maxlen=history)
    for line in lines:
        if pattern in line:
            yield line, previous_lines
        previous_lines.append(line)
        

if __name__ == '__main__':
    with open('/mnt/c/Merge.cs') as f:
        for line, prevlines in search(f, 'dense', 5):
            for pline in prevlines:
                print(pline, end=' ')
            print(line, end='')
            print('-'*100)