human
I am working on the file "ANTLR4-Python/Earley-Parser/Earley-Parser.ipynb".
The first task is:
Earley's Algorithm
Given a context-free grammar $G = \langle V, \Sigma, R, S \rangle$ and a string $s = x_1x_2 \cdots x_n \in \Sigma^$ of length $n$, 
an Earley item* is a pair of the form
$$\langle A \rightarrow \alpha \bullet \beta, k \rangle$$
such that 
- $(A \rightarrow \alpha \beta) \in R\quad$  and
- $k \in {0,1,\cdots,n}$. 
The class EarleyItem represents a single Earley item.
- mVariable is the variable $A$,
- mAlpha is $\alpha$,
- mBeta is $\beta$, and
- mIndex is $k$.
Since we later have to store objects of class EarleyItem in sets, we have to implement the functions
- __eq__,
- __ne__,
- __hash__.
It is easiest to implement __hash__ by first converting the object into a string.  Hence we also
implement the function __repr__, that converts an EarleyItem into a string.
Can you write Python program for it?
assistant
#Here is the Python program you requested.

class EarleyItem():
    def __init__(self, variable, alpha, beta, index):
        self.mVariable = variable
        self.mAlpha    = alpha
        self.mBeta     = beta
        self.mIndex    = index
    
    def __eq__(self, other):
        return isinstance(other, EarleyItem)     and \
               self.mVariable == other.mVariable and \
               self.mAlpha    == other.mAlpha    and \
               self.mBeta     == other.mBeta     and \
               self.mIndex    == other.mIndex
    
    def __ne__(self, other):
        return not self.__eq__(other)
    
    def __hash__(self):
        return hash(self.__repr__())
    
    def __repr__(self):
        alphaStr = ' '.join(self.mAlpha)
        betaStr  = ' '.join(self.mBeta)
        return f'<{self.mVariable} → {alphaStr} • {betaStr}, {self.mIndex}>'