#14804: Remove [] around optional arguments with default values

Mostly just mechanical removal of []. In some rare cases I've pulled the
default value up into the argument list.
diff --git a/Doc/library/trace.rst b/Doc/library/trace.rst
index a2afda1..9cd4996 100644
--- a/Doc/library/trace.rst
+++ b/Doc/library/trace.rst
@@ -149,7 +149,7 @@
        the current tracing parameters.  *cmd* must be a string or code object,
        suitable for passing into :func:`exec`.
 
-    .. method:: runctx(cmd[, globals=None[, locals=None]])
+    .. method:: runctx(cmd, globals=None, locals=None)
 
        Execute the command and gather statistics from the execution with the
        current tracing parameters, in the defined global and local