python: built-in functions

      bytearray: Return mutable array of bytes

      bytes(): get immutable bytes object

      dict(): Create a dictionary

      frozenset: make the iterable immutable

      id(): return identity of the object

      issubclass: Check whether this class is subclass of other class or not

      len(): Get the length of an object

            Get the length of a string

            Find the number of items in a list

            get number of items in the range

            Get number of items in the set

            Get number of items in the frozen set