生成一个包含一段文章中单词频率统计的Python程序。
文章段落
以下是一个简单的 Python 程序，用于计算一段文章中每个单词出现的频率。这个程序将输入的文章作为字符串传递给`word_frequency`函数，然后返回一个字典，其中键是单词，值是该单词在文章中出现的次数。

```python
def word_frequency(text):
    words = text.lower().split()
    frequencies = {}
    for word in words:
        if word in frequencies:
            frequencies[word] += 1
        else:
            frequencies[word] = 1
    return frequencies
```

你可以通过以下方式使用这个函数：

```python
text = "This is a sample sentence with several words. Here are more words. And even more words."
frequencies = word_frequency(text)
for word, frequency in frequencies.items():
    print(f"{word}: {frequency}")
```

输出：

```python
this: 1
is: 1
a: 1
sample: 1
sentence: 1
with: 1
several: 1
words.: 1
here: 1
are: 1
more: 2
words.: 1
and: 1
even: 1
words.: 1
```