ENTRY_POINT = 'next_smallest'
#[PROMPT]

def next_smallest(lst):
    """
    You are given a list of integers.
    Write a function next_smallest() that returns the 2nd smallest element of the list.
    Return None if there is no such element.
    
    next_smallest([1, 2, 3, 4, 5]) == 2
    next_smallest([5, 1, 4, 3, 2]) == 2
    next_smallest([]) == None
    next_smallest([1, 1]) == None
    """
#[SOLUTION]
    lst = sorted(set(lst))
    return None if len(lst) < 2 else lst[1]
#[CHECK]
def check(candidate):

    # Check some simple cases
    assert candidate([1, 2, 3, 4, 5]) == 2
    assert candidate([5, 1, 4, 3, 2]) == 2
    assert candidate([]) == None
    assert candidate([1, 1]) == None
    assert candidate([1,1,1,1,0]) == 1
    assert candidate([1, 0**0]) == None
    assert candidate([-35, 34, 12, -45]) == -35

    # Check some edge cases that are easy to work out by hand.
    assert True

