def applyRules(ch):
    newstr = ""
    if ch == 'F':
        newstr = 'F-F++F-F' # Rule 1
    else:
        newstr = ch # no rules apply so keep the character

    return newstr
def processString(oldStr):
    newstr = ""
    for ch in oldStr:
        newstr = newstr + applyRules(ch)

    return newstr


def createLSystem(numIters, axiom):
    startString = axiom
    endString = ""

def createLSystem(numIters, axiom):
    startString = axiom
    endString = ""
    for i in range(numIters):
        endString = processString(startString)
        startString = endString

    return endString

print(createLSystem(4, "F"))
