------
## 最终结论
```python
def vowels_count(s):
    """Write a function vowels_count which takes a string representing
    a word as input and returns the number of vowels in the string.
    Vowels in this case are 'a', 'e', 'i', 'o', 'u'. Here, 'y' is also a
    vowel, but only when it is at the end of the given word.

    Example:
    >>> vowels_count("abcde")
    2
    >>> vowels_count("ACEDY")
    3
    """
    s = s.lower()
    count = sum(1 for char in s if char in "aeiou")
    
    if s.endswith('y'):
        count += 1

    return count

# Add more test cases.
print(vowels_count("abcde"))       # Output: 2
print(vowels_count("ACEDY"))       # Output: 3
print(vowels_count("hello"))       # Output: 2
print(vowels_count("sky"))         # Output: 1
print(vowels_count("rhythm"))      # Output: 0
print(vowels_count("beautiful"))   # Output: 5
print(vowels_count("syzygy"))      # Output: 1
print(vowels_count("AEIOUY"))      # Output: 6
print(vowels_count(""))            # Output: 0
print(vowels_count("xyzzy"))       # Output: 2
print(vowels_count("queue"))       # Output: 4
print(vowels_count("rhythmy"))     # Output: 1
```