def trimmed_sum(x, limit):
    """prec: x is a numerical list
    postc: finds the sum of all elements of x <= limit"""
    out = 0
    for k in x:
        if k <= limit:
            out += k
def trimmed_sum_better(x, limit):
    return sum([ k for k in x if k <= limit])

def foo(x):
    """prec: x is a numerical list.
    postc: returns the sum of the cubes of the nonnegative elements o x.
    """
    return sum([i**3 for i in x if i >= 0])

x = [-3, 4, -2, 8]
print(foo(x) == 576)
zoo = {"cat": 5, "dog":3, "tapir":9, "okapi":2, "hyena":1}

rare = {k:v for k,v in zoo.items() if v <= 2}
print(rare)