read_lines = set()

with open('mycoolfile.txt') as my_file:
    for line in my_file:
        if line not in read_lines:
            read_lines.add(line)
        else:
            break

        print(line, end="")

print(read_lines)

1fb66b58e47e15dafa3e3578eff1122b3f72bfbd
<mask token>

<mask token>
with open('mycoolfile.txt') as my_file:
    for line in my_file:
        if line not in read_lines:
            read_lines.add(line)
        else:
            break
        print(line, end='')
print(read_lines)

read_lines = set()
with open('mycoolfile.txt') as my_file:
    for line in my_file:
        if line not in read_lines:
            read_lines.add(line)
        else:
            break
        print(line, end='')
print(read_lines)

read_lines = set()

with open('mycoolfile.txt') as my_file:
    for line in my_file:
        if line not in read_lines:
            read_lines.add(line)
        else:
            break

        print(line, end="")

print(read_lines)
