Python TypeError: unsupported operand type(s) for +: 'int' and 'tuple'

I get this error using python2

Traceback (most recent call last):
  File "../../readHBmap1.py", line 298, in <module>
    counter=readFiles().countHbmap(startingLine,numberHbonds,inputHbmap)
  File "../../readHBmap1.py", line 227, in countHbmap
    for i in range(startingLine, startingLine+numberHbonds):
TypeError: unsupported operand type(s) for +: 'int' and 'tuple'

The python code where the error occurs is

def countHbmap(self,startingLine,numberHbonds,inputHbmap):
        counter = []
        for i in range(startingLine, startingLine+numberHbonds):
            line = linecache.getline(inputHbmap, i)
            counter.append(line.count('o'))
        return counter

And line 298 is

counter=readFiles().countHbmap(startingLine,numberHbonds,inputHbmap)