I have folder with many text files some of files has the same exact content to other. How can I merge just the unique content and ignore the duplicates?
I do not remove duplicate lines. My files as the following:

Text file1:

```
Line1
Line1
Line3

```

Text file2:

```
Line1
Line1
Line3

```

Text file3:

```
text1
Line2
text3

```

The result:

```
Line1
Line1
Line3
text1
Line2
text3

```

I tried this but this only combine all of them into one file:

```
import glob
txt_files = glob.glob('*.log')
with open('merged_files.txt','w') as merged_files:
    for f in txt_files:
        for line in open(f,'r'):
            merged_files.write(line)

```

How can I read all the files and write only unique content in single text file?