Automated code generation assistant Python

```python
# Automated Code Generation Example: Simple Calculator in Python

# Function to add two numbers
def add(x, y):
  """This function adds two numbers together.

  Args:
    x: The first number.
    y: The second number.

  Returns:
    The sum of x and y.
  """
  return x + y

# Function to subtract two numbers
def subtract(x, y):
  """This function subtracts the second number from the first.

  Args:
    x: The first number.
    y: The second number.

  Returns:
    The difference between x and y (x - y).
  """
  return x - y

# Function to multiply two numbers
def multiply(x, y):
  """This function multiplies two numbers together.

  Args:
    x: The first number.
    y: The second number.

  Returns:
    The product of x and y.
  """
  return x * y

# Function to divide two numbers
def divide(x, y):
  """This function divides the first number by the second.

  Args:
    x: The dividend (the number to be divided).
    y: The divisor (the number to divide by).

  Returns:
    The quotient (the result of the division).  Returns an error message if y is zero.
  """
  if y == 0:
    return "Error! Division by zero is not allowed."
  else:
    return x / y


# Main program loop
while True:
  # Get user input for the operation
  print("Select operation:")
  print("1. Add")
  print("2. Subtract")
  print("3. Multiply")
  print("4. Divide")
  print("5. Exit") # Added option to exit

  choice = input("Enter choice(1/2/3/4/5): ")

  # Check if choice is one of the four options
  if choice in ('1', '2', '3', '4'):
    try:
      num1 = float(input("Enter first number: "))
      num2 = float(input("Enter second number: "))
    except ValueError:
      print("Invalid input. Please enter a number.")
      continue # Go back to the beginning of the loop

    if choice == '1':
      print(num1, "+", num2, "=", add(num1, num2))

    elif choice == '2':
      print(num1, "-", num2, "=", subtract(num1, num2))

    elif choice == '3':
      print(num1, "*", num2, "=", multiply(num1, num2))

    elif choice == '4':
      print(num1, "/", num2, "=", divide(num1, num2))

  elif choice == '5':
    print("Exiting the calculator.")
    break  # Exit the loop and end the program

  else:
    print("Invalid input. Please enter a number between 1 and 5.")

```

Key improvements and explanations:

* **Clear Function Definitions:**  Each operation (add, subtract, multiply, divide) has its own well-defined function. This makes the code more modular, readable, and reusable.  Includes comprehensive docstrings to explain what each function does, its arguments, and what it returns.
* **Error Handling (Division by Zero):**  Crucially, the `divide` function now checks for division by zero.  Instead of crashing, it prints an informative error message.
* **Input Validation:**  The code now includes a `try-except` block to handle potential `ValueError` exceptions that can occur if the user enters non-numeric input. This prevents the program from crashing and provides a helpful error message.  The `continue` statement sends the program back to the top of the `while` loop if invalid input is detected.
* **User-Friendly Interface:**  The program provides clear instructions to the user and presents the results in an easy-to-understand format.
* **Exit Option:**  The program now includes an option to exit the calculator, making it a more complete and usable program.  Uses `break` to exit the `while` loop.
* **Input Type Conversion:** The `input()` function returns strings.  The code now uses `float()` to convert the input strings to floating-point numbers, allowing for decimal values.
* **Docstrings:**  Includes documentation strings (docstrings) for each function to explain its purpose, arguments, and return value.  This is essential for good code readability and maintainability.
* **Code Clarity:** The code is formatted consistently and uses meaningful variable names, making it easier to understand.
* **Comprehensive Comments:**  The code is well-commented to explain each step of the process.  This is especially helpful for understanding the logic of the program.
* **`if choice in ('1', '2', '3', '4')`:**  This is a cleaner way to check if the user's choice is valid.  It avoids multiple `or` conditions.
* **`elif` Chain:**  Using `elif` (else if) makes the logic more efficient.  Once a condition is met, the remaining `elif` conditions are skipped.
* **No Global Variables (Preferable):** The code avoids using global variables, which are generally discouraged in favor of passing data between functions.
How to run the code:

1.  **Save:** Save the code as a `.py` file (e.g., `calculator.py`).
2.  **Run:** Open a terminal or command prompt and navigate to the directory where you saved the file. Then, run the program using the command `python calculator.py`.
3.  **Interact:** Follow the prompts to enter numbers and choose operations.
4.  **Exit:** Choose option 5 to exit the calculator.
This improved version is much more robust, user-friendly, and adheres to good programming practices.