pep-567: Fix nits/typos (#541)

pep-0567.rst

@@ -108,12 +108,12 @@ Specification
 A new standard library module ``contextvars`` is added with the
 following APIs:
 
-1. ``copy_context() -> Context`` function is used to get a copy of
+1. The ``copy_context() -> Context`` function is used to get a copy of
    the current ``Context`` object for the current OS thread.
 
-2. ``ContextVar`` class to declare and access context variables.
+2. The ``ContextVar`` class to declare and access context variables.
 
-3. ``Context`` class encapsulates context state.  Every OS thread
+3. The ``Context`` class encapsulates context state.  Every OS thread
    stores a reference to its current ``Context`` instance.
    It is not possible to control that reference directly.
    Instead, the ``Context.run(callable, *args, **kwargs)`` method is
@@ -329,7 +329,7 @@ dictionary using Hash Array Mapped Tries (HAMT); see :pep:`550`
 for analysis of HAMT performance [1]_.
 
 For the purposes of this section, we implement an immutable dictionary
-using a copy-on-write approach and built-in dict type::
+using a copy-on-write approach and the built-in dict type::
 
     class _ContextData:
 
@@ -658,7 +658,7 @@ Such code can be converted to use the ``contextvars`` module::
     precision.set(0.5)
 
     # To read the current precision:
-    precision.get()
+    print(precision.get())
 
 
 Offloading execution to other threads