Advanced list processing:
v List comprehensions provide a concise way to apply operations on a list.
v It creates a new list in which each element is the result of applying a given operation in a list.
v It consists of brackets containing an expression followed by a “for” clause, then a list.
v The list comprehension always returns a result list.
list=[ expression for item in list if conditional ]
List inside another list is called nested list.