aData = "$123,421.83"


#Takes in a  string representing some money
#and returns a float representing dollars!
#If it doesn't find a valid number, it returns None!
def parseFloat(aStr):
    newStr = ""

    for letter in aStr:
        if letter in "-0123456789.":
            newStr = newStr + letter

    if len(newStr) > 0:
        answer = float(newStr)
        return(answer)
    else:
        return None


data = parseFloat( aData)
print(data)