<s>
In	O
programming	B-General_Concept
,	O
a	O
docstring	B-Language
is	O
a	O
string	B-Language
literal	I-Language
specified	O
in	O
source	O
code	O
that	O
is	O
used	O
,	O
like	O
a	O
comment	O
,	O
to	O
document	O
a	O
specific	O
segment	O
of	O
code	O
.	O
</s>
<s>
Unlike	O
conventional	O
source	O
code	O
comments	O
,	O
or	O
even	O
specifically	O
formatted	O
comments	O
like	O
docblocks	O
,	O
docstrings	B-Language
are	O
not	O
stripped	O
from	O
the	O
source	O
tree	O
when	O
it	O
is	O
parsed	O
and	O
are	O
retained	O
throughout	O
the	O
runtime	O
of	O
the	O
program	O
.	O
</s>
<s>
Languages	O
that	O
support	O
docstrings	B-Language
include	O
Python	B-Language
,	O
Lisp	B-Language
,	O
Elixir	B-Language
,	O
Clojure	B-Language
,	O
Gherkin	O
,	O
Julia	B-Application
and	O
Haskell	B-Language
.	O
</s>
<s>
Documentation	O
is	O
supported	O
at	O
language	O
level	O
,	O
in	O
the	O
form	O
of	O
docstrings	B-Language
.	O
</s>
<s>
Markdown	O
is	O
Elixir	B-Language
's	O
de	O
facto	O
markup	O
language	O
of	O
choice	O
for	O
use	O
in	O
docstrings	B-Language
:	O
</s>
<s>
In	O
Lisp	B-Language
,	O
docstrings	B-Language
are	O
known	O
as	O
documentation	B-Language
strings	I-Language
.	O
</s>
<s>
The	O
Common	B-Language
Lisp	I-Language
standard	O
states	O
that	O
a	O
particular	O
implementation	O
may	O
choose	O
to	O
discard	O
docstrings	B-Language
whenever	O
they	O
want	O
,	O
for	O
whatever	O
reason	O
.	O
</s>
<s>
When	O
they	O
are	O
kept	O
,	O
docstrings	B-Language
may	O
be	O
viewed	O
and	O
changed	O
using	O
the	O
DOCUMENTATION	O
function	O
.	O
</s>
<s>
The	O
common	O
practice	O
of	O
documenting	O
a	O
code	O
object	O
at	O
the	O
head	O
of	O
its	O
definition	O
is	O
captured	O
by	O
the	O
addition	O
of	O
docstring	B-Language
syntax	O
in	O
the	O
Python	B-Language
language	I-Language
.	O
</s>
<s>
The	O
docstring	B-Language
for	O
a	O
Python	B-Language
code	I-Language
object	O
(	O
a	O
module	O
,	O
class	O
,	O
or	O
function	O
)	O
is	O
the	O
first	O
statement	O
of	O
that	O
code	O
object	O
,	O
immediately	O
following	O
the	O
definition	O
(	O
the	O
'	O
def	O
 '	O
or	O
'	O
class	O
 '	O
statement	O
)	O
.	O
</s>
<s>
The	O
statement	O
must	O
be	O
a	O
bare	O
string	B-Language
literal	I-Language
,	O
not	O
any	O
other	O
kind	O
of	O
expression	O
.	O
</s>
<s>
The	O
docstring	B-Language
for	O
the	O
code	O
object	O
is	O
available	O
on	O
that	O
code	O
object	O
's	O
__doc__	O
attribute	O
and	O
through	O
the	O
help	O
function	O
.	O
</s>
<s>
The	O
following	O
Python	B-Language
file	O
shows	O
the	O
declaration	O
of	O
docstrings	B-Language
within	O
a	O
Python	B-Language
source	O
file	O
:	O
</s>
<s>
Assuming	O
that	O
the	O
above	O
code	O
was	O
saved	O
as	O
,	O
the	O
following	O
is	O
an	O
interactive	O
session	O
showing	O
how	O
the	O
docstrings	B-Language
may	O
be	O
accessed	O
:	O
</s>
