Modify as reviewer suggested

Author: Damien-Chen

Doc/library/traceback.rst

@@ -503,7 +503,9 @@ the module-level functions described above.
 A :class:`!FrameSummary` object represents a single :ref:`frame <frame-objects>`
 in a :ref:`traceback <traceback-objects>`.
 
-.. class:: FrameSummary(filename, lineno, name, lookup_line=True, locals=None, line=None, end_lineno=None, colno=None, end_colno=None)
+.. class:: FrameSummary(filename, lineno, name, *,\
+                        lookup_line=True, locals=None, \
+                        line=None, end_lineno=None, colno=None, end_colno=None)
 
    Represents a single :ref:`frame <frame-objects>` in the
    :ref:`traceback <traceback-objects>` or stack that is being formatted
@@ -542,14 +544,17 @@ in a :ref:`traceback <traceback-objects>`.
    .. attribute:: FrameSummary.end_lineno
 
       The last line number of the source code for this frame.
+      By default, it is ``None`` and is 1-index base.
 
    .. attribute:: FrameSummary.colno
 
       The column number of the source code for this frame.
+      By default, it is ``None`` and is 1-index base.
 
    .. attribute:: FrameSummary.end_colno
 
       The last column number of the source code for this frame.
+      By default, it is ``None`` and is 1-index base.
 
 .. _traceback-example: