Introduction
In Python, sometimes we need to convert a value into a list. However, if the value is already a list, we don't want to create a nested list. In this challenge, you will create a function that takes a value and returns it as a list, unless it is already a list or another iterable.
Cast to List
Write a function cast_list(val) that takes a value as an argument and returns it as a list. If the value is already a list, return it as is. If the value is not a list but is iterable, return it as a list. If the value is not iterable, return it as a single-item list.
def cast_list(val):
return list(val) if isinstance(val, (tuple, list, set, dict)) else [val]
cast_list('foo') ## ['foo']
cast_list([1]) ## [1]
cast_list(('foo', 'bar')) ## ['foo', 'bar']
Summary
In this challenge, you learned how to create a function that casts a value to a list if it is not already a list or another iterable. You used isinstance() to check if the value is iterable and returned it using list() or encapsulated it in a list accordingly.