Calculator.py

expression = ["0", "+", "1", "=" , "1"]
ops = ["-", "=", "+", "/"]

mapdigit = {"0" : 0, "1" : 1 , "2" : 2 ,
            "3" : 3, "4" : 4, "5" : 5, "6" : 6,
            "7" : 7, "8" : 8, "9" : 9, "10" : 10}
def checkdigit(expression, position):
    item = expression[position]
    if( item in onetoten):
        return item
    else:
        return ""
def getPlus(expression):
    scan = 0 
    for scan in range(len(expression)):
        if(expression[scan] == "+"): 
            if(checkdigit(expression, scan - 1) != ""):
                left = expression[scan - 1]
            if(checkdigit(expression, scan + 1) != ""):
                right = expression[scan + 1]
                tree = ["+", [left, right]]
                return tree
            else:
                return ""
tree = getPlus(expression)
root = tree[0] 
left = tree[1][0]
right = tree[1][1]
print(left + root + right + "=" + "1")