Issue #4945: Improved the documenting of boolean arguments in the json module.

Based on patch by Gabriel Genellina.

Author: serhiy-storchaka

Doc/library/json.rst

@@ -102,7 +102,7 @@ Extending :class:`JSONEncoder`::
 
 .. highlight:: bash
 
-Using json.tool from the shell to validate and pretty-print::
+Using :mod:`json.tool` from the shell to validate and pretty-print::
 
     $ echo '{"json":"obj"}' | python -m json.tool
     {
@@ -135,26 +135,27 @@ Basic Usage
    :term:`file-like object`) using this :ref:`conversion table
    <py-to-json-table>`.
 
-   If *skipkeys* is ``True`` (default: ``False``), then dict keys that are not
+   If *skipkeys* is true (default: ``False``), then dict keys that are not
    of a basic type (:class:`str`, :class:`int`, :class:`float`, :class:`bool`,
    ``None``) will be skipped instead of raising a :exc:`TypeError`.
 
    The :mod:`json` module always produces :class:`str` objects, not
    :class:`bytes` objects. Therefore, ``fp.write()`` must support :class:`str`
    input.
 
-   If *ensure_ascii* is ``True`` (the default), the output is guaranteed to
+   If *ensure_ascii* is true (the default), the output is guaranteed to
    have all incoming non-ASCII characters escaped.  If *ensure_ascii* is
-   ``False``, these characters will be output as-is.
+   false, these characters will be output as-is.
 
-   If *check_circular* is ``False`` (default: ``True``), then the circular
+   If *check_circular* is false (default: ``True``), then the circular
    reference check for container types will be skipped and a circular reference
    will result in an :exc:`OverflowError` (or worse).
 
-   If *allow_nan* is ``False`` (default: ``True``), then it will be a
+   If *allow_nan* is false (default: ``True``), then it will be a
    :exc:`ValueError` to serialize out of range :class:`float` values (``nan``,
-   ``inf``, ``-inf``) in strict compliance of the JSON specification, instead of
-   using the JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).
+   ``inf``, ``-inf``) in strict compliance of the JSON specification.
+   If *allow_nan* is true, their JavaScript equivalents (``NaN``,
+   ``Infinity``, ``-Infinity``) will be used.
 
    If *indent* is a non-negative integer or string, then JSON array elements and
    object members will be pretty-printed with that indent level.  An indent level
@@ -174,10 +175,12 @@ Basic Usage
    .. versionchanged:: 3.4
       Use ``(',', ': ')`` as default if *indent* is not ``None``.
 
-   *default(obj)* is a function that should return a serializable version of
-   *obj* or raise :exc:`TypeError`.  The default simply raises :exc:`TypeError`.
+   If specified, *default* should be a function that gets called for objects that
+   can't otherwise be serialized.  It should return a JSON encodable version of
+   the object or raise a :exc:`TypeError`.  If not specified, :exc:`TypeError`
+   is raised.
 
-   If *sort_keys* is ``True`` (default: ``False``), then the output of
+   If *sort_keys* is true (default: ``False``), then the output of
    dictionaries will be sorted by key.
 
    To use a custom :class:`JSONEncoder` subclass (e.g. one that overrides the
@@ -339,7 +342,7 @@ Encoders and Decoders
    ``'false'``.  This can be used to raise an exception if invalid JSON numbers
    are encountered.
 
-   If *strict* is ``False`` (``True`` is the default), then control characters
+   If *strict* is false (``True`` is the default), then control characters
    will be allowed inside strings.  Control characters in this context are
    those with character codes in the 0-31 range, including ``'\t'`` (tab),
    ``'\n'``, ``'\r'`` and ``'\0'``.
@@ -402,26 +405,26 @@ Encoders and Decoders
    for ``o`` if possible, otherwise it should call the superclass implementation
    (to raise :exc:`TypeError`).
 
-   If *skipkeys* is ``False`` (the default), then it is a :exc:`TypeError` to
+   If *skipkeys* is false (the default), then it is a :exc:`TypeError` to
    attempt encoding of keys that are not str, int, float or None.  If
-   *skipkeys* is ``True``, such items are simply skipped.
+   *skipkeys* is true, such items are simply skipped.
 
-   If *ensure_ascii* is ``True`` (the default), the output is guaranteed to
+   If *ensure_ascii* is true (the default), the output is guaranteed to
    have all incoming non-ASCII characters escaped.  If *ensure_ascii* is
-   ``False``, these characters will be output as-is.
+   false, these characters will be output as-is.
 
-   If *check_circular* is ``True`` (the default), then lists, dicts, and custom
+   If *check_circular* is true (the default), then lists, dicts, and custom
    encoded objects will be checked for circular references during encoding to
    prevent an infinite recursion (which would cause an :exc:`OverflowError`).
    Otherwise, no such check takes place.
 
-   If *allow_nan* is ``True`` (the default), then ``NaN``, ``Infinity``, and
+   If *allow_nan* is true (the default), then ``NaN``, ``Infinity``, and
    ``-Infinity`` will be encoded as such.  This behavior is not JSON
    specification compliant, but is consistent with most JavaScript based
    encoders and decoders.  Otherwise, it will be a :exc:`ValueError` to encode
    such floats.
 
-   If *sort_keys* is ``True`` (default ``False``), then the output of dictionaries
+   If *sort_keys* is true (default: ``False``), then the output of dictionaries
    will be sorted by key; this is useful for regression tests to ensure that
    JSON serializations can be compared on a day-to-day basis.
 
@@ -443,9 +446,10 @@ Encoders and Decoders
    .. versionchanged:: 3.4
       Use ``(',', ': ')`` as default if *indent* is not ``None``.
 
-   If specified, *default* is a function that gets called for objects that can't
-   otherwise be serialized.  It should return a JSON encodable version of the
-   object or raise a :exc:`TypeError`.
+   If specified, *default* should be a function that gets called for objects that
+   can't otherwise be serialized.  It should return a JSON encodable version of
+   the object or raise a :exc:`TypeError`.  If not specified, :exc:`TypeError`
+   is raised.
 
    .. versionchanged:: 3.6
       All parameters are now :ref:`keyword-only <keyword-only_parameter>`.

Lib/json/__init__.py

@@ -152,7 +152,7 @@ def dump(obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True,
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
-    If *sort_keys* is ``True`` (default: ``False``), then the output of
+    If *sort_keys* is true (default: ``False``), then the output of
     dictionaries will be sorted by key.
 
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
@@ -214,7 +214,7 @@ def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True,
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
-    If *sort_keys* is ``True`` (default: ``False``), then the output of
+    If *sort_keys* is true (default: ``False``), then the output of
     dictionaries will be sorted by key.
 
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the