Playing with file descriptors

tee.py

@@ -0,0 +1,36 @@
+"""Experimental file-like object that captures output but still send content to
+a real file."""
+
+import io
+import subprocess
+
+
+class Tee(io.FileIO):
+    def close(self):
+        print('TeeClose')
+        return super().close()
+
+    def readline(self, size):
+        print('TeeReadLine')
+        super().readline(size)
+
+    def readlines(self, hint):
+        print('TeeReadLines')
+        super().readlines(size)
+
+    def writelines(self, lines):
+        print('TeeWriteLines')
+        return super().writelines(lines)
+
+    def write(self, b):
+        print('TeeWite:', b)
+        return super().write(b)
+
+
+def main():
+    with Tee('tee.txt', 'w') as target:
+        subprocess.run('ls', stdout=target, check=False)
+
+
+if __name__ == '__main__':
+    main()