请以markdown格式提供一个名为“ Skill in Python Programming ”的代码片段，要求该代码片段展示如何通过Python打印出斐波那契数列的前20个数字。注意代码规范，注释清晰。
user
```markdown
# Skill in Python Programming: Fibonacci Sequence

## Introduction
In this snippet, we will write a Python program to print the first 20 numbers of the Fibonacci sequence. The Fibonacci sequence is a series of numbers where each number is the sum of the two preceding ones, usually starting with 0 and 1.

## Code Example

```python
def fibonacci(n):
    """
    Generate a list containing the Fibonacci sequence up to the n-th number.
    
    Parameters:
    - n: The number of Fibonacci numbers to generate.
    
    Returns:
    A list of the first n Fibonacci numbers.
    """
    fib_sequence = [0, 1]
    for i in range(2, n):
        next_value = fib_sequence[-1] + fib_sequence[-2]
        fib_sequence.append(next_value)
    return fib_sequence

# Print the first 20 Fibonacci numbers
n = 20
fib_numbers = fibonacci(n)
print("The first 20 Fibonacci numbers are:")
print(fib_numbers)
```

## Running the Code
To run the code above, simply copy it into a Python environment or script file and execute it. The program defines a function `fibonacci(n)` that generates the Fibonacci sequence up to the n-th number and then prints the first 20 numbers.

## Explanation
- **Function Definition**: `fibonacci(n)` is defined to take an integer `n` and return a list of the first `n` Fibonacci numbers.
- **Initial Values**: The list `fib_sequence` is initialized with the first two Fibonacci numbers, 0 and 1.
- **Looping and Sequence Generation**: A `for` loop runs from 2 to `n-1`, calculating each subsequent Fibonacci number by summing the last two numbers in the list.
- **Output**: The final list of 20 Fibonacci numbers is printed to the console.

## Conclusion
This code snippet demonstrates a simple and efficient way to generate and print the Fibonacci sequence using Python. It can be easily modified to generate more or fewer numbers in the sequence.
```
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