aider: Added diff_files.py script that reads two file names from the command line, reads the contents of the files, and then uses the difflib module to print their differences.

# Context:
USER: read 2 files named on the cmd line, use difflib to print their differences
ASSISTANT: To achieve this, we'll create a new Python script that reads two file names from the command line, reads the contents of the files, and then uses the `difflib` module to print their differences.

1. Create a new Python script called `diff_files.py` in the `aider` directory.
2. Import the necessary modules: `sys` and `difflib`.
3. Read the file names from the command line arguments.
4. Read the contents of the files.
5. Use `difflib.unified_diff()` to generate the differences.
6. Print the differences.

Here's the code for the new `diff_files.py` script:

```python
aider/diff_files
^C KeyboardInterrupt
USER: put it in `aider/diffs.py`

aider/diffs.py

@@ -0,0 +1,23 @@
+import sys
+import difflib
+
+def main():
+    if len(sys.argv) != 3:
+        print("Usage: python diffs.py file1 file2")
+        sys.exit(1)
+
+    file1, file2 = sys.argv[1], sys.argv[2]
+
+    with open(file1, 'r') as f1:
+        content1 = f1.readlines()
+
+    with open(file2, 'r') as f2:
+        content2 = f2.readlines()
+
+    differences = list(difflib.unified_diff(content1, content2, fromfile=file1, tofile=file2))
+
+    for line in differences:
+        sys.stdout.write(line)
+
+if __name__ == "__main__":
+    main()