Article for Python 3 built-in function (len)

Challenge-Logical-Order-In-If-Else-Statements.md

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+# Challenge Logical Order in If Else Statements
+
+Order is important in `if`, `else if` and `else` statements.
+
+The loop is executed from top to bottom so you will want to be careful of which statement comes first.
+
+Take these two functions as an example.
+
+## Examples:
+
+```javascript
+function foo(x) {
+  if (x < 1) {
+    return "Less than one";
+    } 
+  else if (x < 2) {
+    return "Less than two";
+    } 
+  else {
+    return "Greater than or equal to two";
+    }
+}
+```
+
+And the second just switches the order of the statements:
+
+```javascript
+function bar(x) {
+  if (x < 2) {
+    return "Less than two";
+    } 
+  else if (x < 1) {
+    return "Less than one";
+    }
+  else {
+    return "Greater than or equal to two";
+    }
+}
+```
+
+While these two functions look nearly identical, if we pass a number to both we get different outputs.
+
+```javascript
+foo(0) // "Less than one" 
+
+bar(0) // "Less than two"
+```
+
+So be careful while using the `if`, `else if` and `else` statements and always remember that these are executed from top to bottom. Keep this in mind placing your statements accordingly so that you get the desired output.
+
+

Python-Function-LEN.md

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+# Python len(x)
+
+`len()` is a built in function in Python 3. This method returns the length (the number of items) of an object. It takes one argument `x`. 
+
+## Arguments
+
+It takes one argument `x` - argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).
+
+## Return Value
+
+This function returns the number of elements in the list
+
+## Code Sample
+
+```python
+list1 = [123, 'xyz', 'zara'] 
+str1 = 'basketball'
+print(len(list1)) # prints 3
+print(len(str1)) # prints 10
+```
+
+:rocket: [Run Code](https://repl.it/CUmt)
+
+[Official Docs](https://docs.python.org/3/library/functions.html#len)