在Compute函数里调用one_step函数显示函数未定义，哪里出错了呢
def __init__(self,fa_description):
self.fa = fa_description
self.state = self.fa['start']
def one_step(self,symbol):
"""
takes a symbol (a string) and returns a state
it is the state arrived at given the symbol at the current state
"""
self.state = self.transitions[self.state,symbol]
# write code here
return self.state # do not take this as a hint
def compute(self,string):
"""
takes a string and put the FA in the start state, then applies one_step
to each symbol in the string.
returns True if the FA ends in an accepting state; else returns False
"""
self.state = self.fa['start']
for letter in string:
one_step(self,letter)
if(self.state == self.fa['start']):
return True
# write code here
return False # do not takes this as a hint
#end class SimpleFiniteAutomata
