Changed in doc links to ref links in markdown. Edited and fixed code examples. (exercism#2788)

Author: BethanyG

concepts/strings/about.md

@@ -1,61 +1,120 @@
-Pythons string type `str` can be very powerful. At its core, a `str` is an immutable [text sequence](https://docs.python.org/3/library/stdtypes.html#text-sequence-type-str) of [Unicode code points](https://stackoverflow.com/questions/27331819/whats-the-difference-between-a-character-a-code-point-a-glyph-and-a-grapheme). There is no separate "character" or "char" type in Python.
+Pythons `str` (_string_) type can be very powerful. At its core, a `str` is an immutable [text sequence][text sequence] of [Unicode code points][unicode code points]. There is no separate "character" or "rune" type in Python.
 
-Like any [sequence type](https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range), code points or "characters" within a string can be referenced by 0-based index number, and can be copied in whole or in part via _slice notation_. Since there is no separate “character” type, indexing a string produces a new `str` of length 1 (_for example "exercism"[0] == "exercism"[0:1] == "e"_). Strings support all [common sequence operations](https://docs.python.org/3/library/stdtypes.html#common-sequence-operations), and individual code points or "characters" can be iterated through in a loop via `for item in`.
+Like any [sequence type][sequence type], code points within a `str` can be referenced by 0-based index number and can be copied in whole or in part via _slice notation_. Since there is no separate “character” type, indexing a string produces a new `str` of length 1:
 
-For a deep dive on what information a `str` encodes (or, _"how does the computer know how to translate zeroes and ones into letters?"_), [this blog post is enduringly helpful][joel-on-text].
+```python
+
+>>> website = "exercism"
+>>> type(website[0])
+<class 'str'>
+
+>>> len(website[0])
+1
+
+>>> website[0] == website[0:1] == 'e'
+True
+```
+
+Strings support all [common sequence operations][common sequence operations]. Individual code points can be iterated through in a loop via **`for item in`**.
+
+```python
+
+>>> exercise = 'လေ့ကျင့်'
+
+#note that there are more code points than percieved glyphs or characters
+>>> for code_point in exercise:
+...    print(code_point)
+...
+လ
+ေ
+့
+က
+ျ
+င
+်
+့
+```
+
+For a deep dive on what information a string encodes (or, _"how does the computer know how to translate zeroes and ones into letters?"_), [this blog post is enduringly helpful][joel-on-text]. Additionally, the docs provide a [unicode HOWTO][unicode how-to] that discusses Pythons support for the Unicode specification in the `str`, `bytes` and `re` modules, and some common issues.
 
-Strings can be transformed by [various methods](https://docs.python.org/3/library/stdtypes.html#string-methods), split into letters/symbols, and joined together via [`.join()`](https://docs.python.org/3/library/stdtypes.html#str.join) or `+` to create larger strings . Due to their immutability, any transformations applied to a `str` return a new `str`.
+Strings can be transformed by [various methods][str-methods], split into code points via [`.split()`][str-split], or joined together into larger strings via [`.join()`][str-join] or `+`. Due to their _immutability_, any transformations applied to strings return new `str` objects.
 
 ### Construction
 
 The simplest way to create a `str` literal is by delimiting it with `"` or `'`. Strings can also be written across multiple lines by using triple quotes (`"""` or `'''`) .
 
-````python
-single_quoted = 'Single quotes allow "double quoting" without "escape" characters.'
+```python
+
+>>> single_quoted = 'Single quotes allow "double quoting" without "escape" characters.'
 
-double_quoted = "Double quotes allow embedded 'single quoting' without 'escape' characters".
+>>> double_quoted = "Double quotes allow embedded 'single quoting' without 'escape' characters".
 
-triple_quoted =  '''Three single quotes or double quotes in a row allow for multi-line string literals.  You will most often encounter these as "doc strings" or "doc tests" written just below the first line of a function or class definition.  They are often used with auto documentation tools.'''
+>>> triple_quoted =  '''Three single quotes or double quotes in a row allow for multi-line string literals.  You will most often encounter these as "doc strings" or "doc tests" written just below the first line of a function or class definition.  They are often used with auto documentation tools.'''
 String literals that are part of a single expression and are separated only by white space are _implicitly concatenated_ into a single string literal:
 
-```python
-("I do not "
-"like "
-"green eggs and ham.") == "I do not like green eggs and ham."```
 
+#if you put seperate strings within parenthesis, they will be *implicitly concatenated* by the interpreter
+>>> ("I do not "
+"like "
+"green eggs and ham.") == "I do not like green eggs and ham."
+True
+```
 
-Additionally,  [interpolated](https://en.wikipedia.org/wiki/String_interpolation) strings (`f-strings`) can be formed:
+Additionally, [interpolated][f-strings] strings (`f-strings`) can be formed:
 
 ```python
 my_name = "Praveen"
 
 intro_string = f"Hi! My name is {my_name}, and I'm happy to be here!"
 
 >>>print(intro_string)
-Hi! My name is Praveen, and I'm happy to be here!```
+Hi! My name is Praveen, and I'm happy to be here!
+```
 
-Finally, the  [`str()` constructor](https://docs.python.org/3/library/stdtypes.html#str) can be used to create/coerce strings from other objects/types.  However, the `str` constructor _**will not iterate**_ through an object , so if something like a `list` of elements needs to be connected, `.join()` is a better option:
+Finally, the [`str()` constructor][str-constructor] can be used to create/coerce strings from other objects/types. However, the `str` constructor _**will not iterate**_ through an object , so if something like a `list` of individual elements needs to be connected, `.join()` is a better option:
 
 ```python
 >>> my_number = 675
 >>> str(my_number)
 '675'
 
+#this is a bit surprising, as it will make the entire data structure, complete with the brackets, into a str
 >>> my_list = ["hen", "egg", "rooster"]
 >>> str(my_list)
 "['hen', 'egg', 'rooster']"
 
->>> ' '.join(my_list)
-'hen egg rooster'```
 
+#however, using .join() will iterate and form a string from individual elements
+>>> ' '.join(my_list)
+'hen egg rooster'
+```
 
 ### Formatting
 
-Python provides a rich set of tools for [formatting](https://docs.python.org/3/library/string.html#custom-string-formatting) and [templating](https://docs.python.org/3/library/string.html#template-strings) strings, as well as more sophisticated text processing through the [re (_regular expressions_)](https://docs.python.org/3/library/re.html), [difflib (_sequence comparison_)](https://docs.python.org/3/library/difflib.html), and [textwrap](https://docs.python.org/3/library/textwrap.html) modules.   For a great introduction to string formatting in Python, see [this post at Real Python](https://realpython.com/python-string-formatting/).
-
-For more details on string methods, see [Strings and Character Data in Python](https://realpython.com/python-strings/) at the same site.
-
-###  Related types and encodings
-
-In addition to `str` (a *text* sequence), Python has corresponding  [binary sequence types](https://docs.python.org/3/library/stdtypes.html#binaryseq) `bytes` (a *binary* sequence),  `bytearray` and `memoryview` for the efficient storage and handling of binary data.  Additionally, [Streams](https://docs.python.org/3/library/asyncio-stream.html#streams) allow sending and receiving binary data over a network connection without using callbacks.
-````
+Python provides a rich set of tools for [formatting][str-formatting] and [templating][template-strings] strings, as well as more sophisticated text processing through the [re (_regular expressions_)][re], [difflib (_sequence comparison_)][difflib], and [textwrap][textwrap] modules. For a great introduction to string formatting in Python, see [this post at Real Python][real python string formatting]. For more details on string methods, see [Strings and Character Data in Python][strings and characters] at the same site.
+
+### Related types and encodings
+
+In addition to `str` (a _text_ sequence), Python has corresponding [binary sequence types][binary sequence types] summarized under [binary data services][binary data services] -- `bytes` (a _binary_ sequence), `bytearray`, and `memoryview` for the efficient storage and handling of binary data. Additionally, [Streams][streams] allow sending and receiving binary data over a network connection without using callbacks.
+
+[text sequence]: https://docs.python.org/3/library/stdtypes.html#text-sequence-type-str
+[unicode code points]: https://stackoverflow.com/questions/27331819/whats-the-difference-between-a-character-a-code-point-a-glyph-and-a-grapheme
+[sequence type]: https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range
+[common sequence operations]: https://docs.python.org/3/library/stdtypes.html#common-sequence-operations
+[joel-on-text]: https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/
+[str-methods]: https://docs.python.org/3/library/stdtypes.html#string-methods
+[str-join]: https://docs.python.org/3/library/stdtypes.html#str.join
+[f-strings]: https://en.wikipedia.org/wiki/String_interpolation
+[str-constructor]: https://docs.python.org/3/library/stdtypes.html#str
+[str-formatting]: https://docs.python.org/3/library/string.html#custom-string-formatting
+[template-strings]: https://docs.python.org/3/library/string.html#template-strings
+[re]: https://docs.python.org/3/library/re.html
+[difflib]: https://docs.python.org/3/library/difflib.html
+[textwrap]: https://docs.python.org/3/library/textwrap.html
+[real python string formatting]: https://realpython.com/python-string-formatting/
+[strings and characters]: https://realpython.com/python-strings/
+[binary sequence types]: https://docs.python.org/3/library/stdtypes.html#binaryseq
+[streams]: https://docs.python.org/3/library/asyncio-stream.html#streams
+[unicode how-to]: https://docs.python.org/3/howto/unicode.html
+[str-split]: https://docs.python.org/3/library/stdtypes.html#str.split
+[binary data services]: https://docs.python.org/3/library/binary.html#binaryservices