Python solve Algorithm

# author:           Marcin Cherek
# python version:   3.4
# Date:             5 of Mai 2016
# language:         English
# Title:            solve Algorithm python implementation
import decimal
import logging

logging.basicConfig()
logger= logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#Prepares the the calculation
#this method splits the Operators
#from the Numbers
def _prepare(calculation):
        for i in ["+","-","*","/"]:
                calculation=calculation.replace(i,";"+i+";")
        return calculation.split(";")

#Replaces the sub calculation
#with the Result of it
def _replaceRes(deb,result,zähler):
        deb[zähler-1]=""
        deb[zähler]=""
        deb[zähler+1]=result
        return deb

#Normal calculation of two
#Numebers and one Operator
def _calc(z1,z2,op):
        if(op=="+"):return z1+z2
        elif(op=="-"):return z1-z2
        elif(op=="*"):return z1*z2
        elif(op=="/"):return z1/z2
        
#Shrinks the Array
#It removes the empty elements
def _popArr(deb):
        p=0
        while p<len(deb):
            if deb[p]=="":
                deb.pop(p)
                continue
            p+=1
        return deb

#Most important method
#It iterates the calculation
#and corrdinates the subcalcs with the
#results of it
def _solve_simple(deb,op):
        result=0;zähler=0
        for i in deb:
            if i==op:
                logger.info(deb)
                result=_calc(decimal.Decimal(deb[zähler-1]),decimal.Decimal(deb[zähler+1]),op)
                _replaceRes(deb,result,zähler)
                result=0
            zähler+=1
        deb = _popArr(deb)
        return deb

#Calls the simple Alg
#First of course */ and after that +-
def solve(calculation):
        calculation = _prepare(calculation)
        for i in ["*","/","+","-"]:
                calculation=_solve_simple(calculation,i)
        return decimal.Decimal(calculation[len(calculation)-1])