Final answer:
To modify the script file to a single function file, create a function that accepts weight and height as input arguments and calculates the BMI. Capture the calculated BMI in a new variable and add error handling code to validate the input arguments.
Step-by-step explanation:
To modify the written script file to a single function file, we need to create a function that accepts weight and height as input arguments.
We can then calculate the BMI within the function using the formula BMI = (weight * 703) / (height^2). The calculated BMI can be captured in a new variable within the function and saved in the workspace.
To check for any errors, we can add error handling code to validate the input arguments and ensure they are valid numbers.