bpo-36686: Improve the documentation of the std* params in loop.subprocess_exec (GH-13586)



https://bugs.python.org/issue36686
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index e5cd14b..68105ee 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -1555,6 +1555,7 @@
                                stderr=subprocess.PIPE,
                                universal_newlines=False,
                                shell=True, bufsize=0,
+                               encoding=None, errors=None, text=None,
                                **kwargs):
         if not isinstance(cmd, (bytes, str)):
             raise ValueError("cmd must be a string")
@@ -1564,6 +1565,13 @@
             raise ValueError("shell must be True")
         if bufsize != 0:
             raise ValueError("bufsize must be 0")
+        if text:
+            raise ValueError("text must be False")
+        if encoding is not None:
+            raise ValueError("encoding must be None")
+        if errors is not None:
+            raise ValueError("errors must be None")
+
         protocol = protocol_factory()
         debug_log = None
         if self._debug:
@@ -1580,13 +1588,22 @@
     async def subprocess_exec(self, protocol_factory, program, *args,
                               stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE, universal_newlines=False,
-                              shell=False, bufsize=0, **kwargs):
+                              shell=False, bufsize=0,
+                              encoding=None, errors=None, text=None,
+                              **kwargs):
         if universal_newlines:
             raise ValueError("universal_newlines must be False")
         if shell:
             raise ValueError("shell must be False")
         if bufsize != 0:
             raise ValueError("bufsize must be 0")
+        if text:
+            raise ValueError("text must be False")
+        if encoding is not None:
+            raise ValueError("encoding must be None")
+        if errors is not None:
+            raise ValueError("errors must be None")
+
         popen_args = (program,) + args
         for arg in popen_args:
             if not isinstance(arg, (str, bytes)):