text = "hello+there$"
position = 0
lval = None

def parseLetter(): # a | b | ... | y | z
    global text, position, lval
    if text[position] < "a" or text[position] > "z": return False
    lval = text[position]
    position += 1
    return True

def parseIdentifier(): # letter | letter identifier
    global text, position, lval
    start = position
    if not parseLetter(): return False
    parseIdentifier()
    lval = text[start:position]
    return True

print(parseIdentifier())
print(position)
print(lval)