class TokenStream:
    def __init__(self, input_stream):
        self.input_stream = input_stream

    def is_whitespace(self, char):
        return char in ' \t'

    def is_digit(self, char):
        return char.isdigit()

    def is_operator(self, char):
        return char in '+*'

    def read_while(self, predicate_func):
        _str = ""
        while not self.input_stream.is_eof() and predicate_func(self.input_stream.peek()):
            _str += self.input_stream.next()
        return _str

    def read_number(self):
        number = self.read_while(self.is_digit)
        return {'type': 'num', 'value': int(number)}

    def read_operator(self):
        operator = self.read_while(self.is_operator)
        return {'type': 'op', 'value': operator}

    def read_next(self):
        _ = self.read_while(self.is_whitespace)
        if self.input_stream.is_eof():
            return None
        char = self.input_stream.peek()
        if self.is_digit(char):
            return self.read_number()
        if self.is_operator(char):
            return self.read_operator()
        self.input_stream.croak("Can't handle character: " + char)
        self.input_stream.next()
        return None
operators = {
    '+': {'prec': 10, 'assoc': 'left'},
    '*': {'prec': 20, 'assoc': 'left'}
}

class TokenStream:
    def __init__(self, input_stream):
        self.input_stream = input_stream

    def is_whitespace(self, char):
        return char in ' \t'

    def is_digit(self, char):
        return char.isdigit()

    def is_operator(self, char):
        return char in operators

    def read_while(self, predicate_func):
        _str = ""
        while not self.input_stream.is_eof() and predicate_func(self.input_stream.peek()):
            _str += self.input_stream.next()
        return _str

    def read_number(self):
        number = self.read_while(self.is_digit)
        return {'type': 'num', 'value': int(number)}

    def read_operator(self):
        operator = self.read_while(self.is_operator)
        return {'type': 'op', 'value': operator}

    def read_next(self):
        _ = self.read_while(self.is_whitespace)
        if self.input_stream.is_eof():
            return None
        char = self.input_stream.peek()
        if self.is_digit(char):
            return self.read_number()
        if self.is_operator(char):
            return self.read_operator()
        self.input_stream.croak("Can't handle character: " + char)
        self.input_stream.next()
        return None
Define precedence and associativity for operators
Define precedence and associativity for operators

+ operators = {
+     '+': {'prec': 10, 'assoc': 'left'},
+     '*': {'prec': 20, 'assoc': 'left'}
+ }
+ 
  class TokenStream:
      def __init__(self, input_stream):
          self.input_stream = input_stream
  
      def is_whitespace(self, char):
          return char in ' \t'
  
      def is_digit(self, char):
          return char.isdigit()
  
      def is_operator(self, char):
-         return char in '+*'
+         return char in operators
  
      def read_while(self, predicate_func):
          _str = ""
          while not self.input_stream.is_eof() and predicate_func(self.input_stream.peek()):
              _str += self.input_stream.next()
          return _str
  
      def read_number(self):
          number = self.read_while(self.is_digit)
          return {'type': 'num', 'value': int(number)}
  
      def read_operator(self):
          operator = self.read_while(self.is_operator)
          return {'type': 'op', 'value': operator}
  
      def read_next(self):
          _ = self.read_while(self.is_whitespace)
          if self.input_stream.is_eof():
              return None
          char = self.input_stream.peek()
          if self.is_digit(char):
              return self.read_number()
          if self.is_operator(char):
              return self.read_operator()
          self.input_stream.croak("Can't handle character: " + char)
          self.input_stream.next()
          return None
Define precedence and associativity for operators
## Code Before:
class TokenStream:
    def __init__(self, input_stream):
        self.input_stream = input_stream

    def is_whitespace(self, char):
        return char in ' \t'

    def is_digit(self, char):
        return char.isdigit()

    def is_operator(self, char):
        return char in '+*'

    def read_while(self, predicate_func):
        _str = ""
        while not self.input_stream.is_eof() and predicate_func(self.input_stream.peek()):
            _str += self.input_stream.next()
        return _str

    def read_number(self):
        number = self.read_while(self.is_digit)
        return {'type': 'num', 'value': int(number)}

    def read_operator(self):
        operator = self.read_while(self.is_operator)
        return {'type': 'op', 'value': operator}

    def read_next(self):
        _ = self.read_while(self.is_whitespace)
        if self.input_stream.is_eof():
            return None
        char = self.input_stream.peek()
        if self.is_digit(char):
            return self.read_number()
        if self.is_operator(char):
            return self.read_operator()
        self.input_stream.croak("Can't handle character: " + char)
        self.input_stream.next()
        return None
## Instruction:
Define precedence and associativity for operators
## Code After:
operators = {
    '+': {'prec': 10, 'assoc': 'left'},
    '*': {'prec': 20, 'assoc': 'left'}
}

class TokenStream:
    def __init__(self, input_stream):
        self.input_stream = input_stream

    def is_whitespace(self, char):
        return char in ' \t'

    def is_digit(self, char):
        return char.isdigit()

    def is_operator(self, char):
        return char in operators

    def read_while(self, predicate_func):
        _str = ""
        while not self.input_stream.is_eof() and predicate_func(self.input_stream.peek()):
            _str += self.input_stream.next()
        return _str

    def read_number(self):
        number = self.read_while(self.is_digit)
        return {'type': 'num', 'value': int(number)}

    def read_operator(self):
        operator = self.read_while(self.is_operator)
        return {'type': 'op', 'value': operator}

    def read_next(self):
        _ = self.read_while(self.is_whitespace)
        if self.input_stream.is_eof():
            return None
        char = self.input_stream.peek()
        if self.is_digit(char):
            return self.read_number()
        if self.is_operator(char):
            return self.read_operator()
        self.input_stream.croak("Can't handle character: " + char)
        self.input_stream.next()
        return None