def squares(n):
    """return a list of the first n perfect squares"""
    ans = []
    for i in range(n):
        ans.append((i+1)**2)

    return ans



def even_only( l ):
    """return a list containing only the even elements of l"""
    ans = []
    for i in l:
        if (i%2) == 0:
            ans.append(i)
    return ans