Article: Python Function ID (#962)

* Added Python-Function-ID.md

For issue #819

* Removed duplicate line

converted object heading to  h4 and removed duplicate line about return value.

* Removed different python implementation details

The different python implementation details are confusing and could be ignored. The id() function is not used that much so omitting the statement makes more sense.

Python-Function-ID.md

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+# Python id(object)
+
+`id()` is a built-in function in Python 3, which returns the *identity* of an object. The *identity* is a unique integer for that object during its lifetime. This is also the address of the object in memory.
+
+## Argument
+
+#### object
+
+The `object` argument can typically be a `int`,`float`, `str`,`list`, `dict`, `tuple` etc.
+
+## Code Sample
+
+```python
+a = 2
+print(id(a)) #=> 140454723286976 (Values returned by id() might be different for different users)
+
+b = 3
+print(id(b)) #=> 140454723287008
+
+c = 2
+print(id(c)) #=> 140454723286976 (This is same as id(a) since they both contain the same value and hence have same memory address)
+
+print(id(a) == id(b)) #=> False (since a and b have different values stored in them)
+print(id(a) == id(c)) #=> True (since a and c have same values stored in them)
+
+d = 1.1
+e = 1.1 
+print(id(d) == id(e)) #=> True (since d and e have same values stored in them)
+
+str1 = 'hello'
+str2 = 'hello'
+print(id(str1) == id(str2)) #=> True (since str1 and str2 have same values stored in them)
+
+# For complex objects like lists, tuples, dictionaries etc. id() would give a unique integer even if the content of those containers is same.
+tup1 = (1,1)
+tup2 = (1,1)
+print(id(tup1) == id(tup2)) #=> False
+```
+
+:rocket: [REPL It!](https://repl.it/CQw7/1)
+
+[Official Docs](https://docs.python.org/3/library/functions.html#id)