Extracted text: import json def load_bimmypp(filename): with open (filename) as infile: return json.load (infile) def validate(bpp): """Returns True if this is a valid bimmypp program, or if it finds a problem, raises a ValueError.""" # If we get passed an int, it's OK! # If it's a list, you must check... # Is it of length 3? # Assuming it's of length 3, is the first thing in the list one of # "add", # If those aren't true, raise a ValueError. # Finally, you have to run validate (recursively) on the left operand and # right operand. (so things at index 1 and 2 in the list) # If it's anything else other than an int or a list, raise a ValueError. 'sub", "mul", or "div"? pass def evaluate(bpp): """Evaluate a bpp expression. Returns the result of evaluating the program. Might also raise a ValueError, if we end up dividing by 0. # If we get passed an int, then that's it! Just return the int value. # If we get passed a list, then we have to evaluate the expression. # Get the operator out of the list (at the 0 index). # RECURSIVELY EVALUATE the operands. # If the operator is "add", then add the two operands! # Likewise for sub and mul. # If we're doing division, we must check for 0. # If the right operator is 0, then raise a ValueError with the message # "divide by zero". # Assuming everything worked, return the result! pass def run_bimmypp(filename): "" "Function for running a bimmypp program. Takes a filename and executes the file. You don't have to make any changes to this function.""" try: bpp = load_bimmypp(filename) except json.decoder.JSONDecodeError: print ("Could not load bimmypp file") return None except FileNotFoundError: print("no such file: " return None filename) try: valid = validate(bpp) except ValueError as e: print(e) return None try: value = evaluate(bpp) print("Success!") print("we got:", value) return value except ValueError as e: print (e) return None
Extracted text: 1. validate Takes anything at all (any Python value) and returns True if that value is a valid bimmy++ expression. A Python value is a valid bimmy++ expression if it is either an integer or a list describing a computation (in the way make sure to recursively check the children!). This function will always either return True or raise a described above -- ValueError. For style points (which don't affect your grade, just your reputation), put helpful error messages in your ValueError objects! 2. evaluate Takes a valid bimmy++ expression and evaluates it! (you only have to handle valid bimmy++ expressions here -- they have already been validated by validate , above) If the expression is an integer, just return that integer! If the expression describes a computation (ie, it is a list), then recursively evaluate its children (the operands for the computation). "add", "sub", and "mul" are pretty straightforward, but some care needs to be taken with "div". Make sure that "div" does integer division (use Python's // operator), and if you are about to divide by 0, raise a ValueError with the message "divide by zero".