Plows shit2

source2 = "1+2-3*4+3-5/2"
parsed = []
source = list(source2)
parsed2 = []

def calculate_string(string):
    try:
        for subs in string:
            if subs.isdigit():
                parsed.append(subs)
            if subs == '+':
                parsed.append('+')
            if subs == '-':
                parsed.append('-')
            if subs == '*':
                first = float(string[string.index(subs) - 1])
                second = float(string[string.index(subs) + 1])
                result = first * second
                parsed.append(result)
                parsed.remove(string[string.index(subs) - 1])
                string.remove(string[string.index(subs) + 1])

            if subs == '/':
                first = float(string[string.index(subs) - 1])
                second = float(string[string.index(subs) + 1])
                parsed.append(first / second)
                parsed.remove(string[string.index(subs) - 1])
                string.remove(string[string.index(subs) + 1])
        print "First parsed round = "
        print parsed

        for subs2 in parsed:
            if subs2 == '+':
                first2 = float(parsed[parsed.index(subs2) - 1])
                second2 = float(parsed[parsed.index(subs2) + 1])
                result2 = first2 + second2
                parsed2.append(result2)
                parsed.remove(parsed[parsed.index(subs2) + 1])
            if subs2 == '-':
                first3 = float(parsed[parsed.index(subs2) - 1])
                second3 = float(parsed[parsed.index(subs2) + 1])
                result3 = first3 - second3
                parsed2.append(result3)
                parsed.remove(parsed[parsed.index(subs2) + 1])

    except (ValueError, IndexError):
        print "end"

    return parsed2


if __name__ == '__main__':
    print calculate_string(source)