Final Answer:
The unsupported format string error is due to the attempt to format a non-string value using a format specifier that's incompatible. Specifically, attempting to format an integer as a float in the 'print' statement at the end of the 'submit' function causes this issue.
Step-by-step explanation:
In the 'submit' function, the line `print(f'Name:{name} Score:{score:.2f}')` tries to format 'score', which is an integer received from the user, as a floating-point number with two decimal places. However, the format specifier ':.2f' is designed for floating-point values, not integers. To resolve this error, adjust the formatting to accommodate integers by removing the '.2f' formatting from the 'print' statement or by converting 'score' to a float using `float(score)` before formatting it in the print statement.
Additionally, ensuring proper validation and type-checking for user inputs, such as scores and grade basis, within the 'submit' function using 'is_valid_score()' and 'is_valid_graded()' functions respectively, can enhance the program's robustness. Implementing error handling mechanisms to prompt users for valid inputs in case of incorrect entries would also improve the overall user experience and program reliability.
Maintaining consistency in data types and using appropriate format specifiers in 'print' statements based on the data being processed helps avoid compatibility issues and prevents errors related to unsupported format strings.
Improving the code's documentation with comments and informative variable names could enhance readability and aid in identifying potential issues within the program, facilitating smoother debugging and maintenance processes.