Python parsing error message functions - parsing

Question

The code below was created by me with the help of many SO veterans:
The code takes an entered math expression and splits it into operators and operands for later use. I have created two functions, the parsing function that splits, and the error function. I am having problems with the error function because it won't display my error messages and I feel the function is being ignored when the code runs. An error should print if an expression such as this is entered: 3//3+4,etc. where there are two operators together, or there are more than two operators in the expression overall, but the error messages dont print. My code is below:
def errors():
numExtrapolation,opExtrapolation=parse(expression)
if (len(numExtrapolation) == 3) and (len(opExtrapolation) !=2):
print("Bad1")
if (len(numExtrapolation) ==2) and (len(opExtrapolation) !=1):
print("Bad2")
def parse(expression):
operators= set("*/+-")
opExtrapolate= []
numExtrapolate= []
buff=[]
for i in expression:
if i in operators:
numExtrapolate.append(''.join(buff))
buff= []
opExtrapolate.append(i)
opExtrapolation=opExtrapolate
else:
buff.append(i)
numExtrapolate.append(''.join(buff))
numExtrapolation=numExtrapolate
#just some debugging print statements
print(numExtrapolation)
print("z:", len(opExtrapolation))
return numExtrapolation, opExtrapolation
errors()
Any help would be appreciated. Please don't introduce new code that is any more advanced than the code already here. I am looking for a solution to my problem... not large new code segments. Thanks.

Answer 1

The errors() function is called after parse() returns because it appears inside the body of parse(). Hopefully that is a typo.
For this particular input, numExtrapolate is appended with an empty buffer because there is no operand between / and /. That makes its length 4 and your check for Bad1 fails. So put a check like this
if buff:
numExtrapolate.append(''.join(buff))