An equals filter chain.

        >>> request_time = EventExpression('request', 'elapsed_ms')
        >>> filtered = request_time.eq('path', '/')
        >>> print(filtered)
        request(elapsed_ms).eq(path, "/")

def eq(self, event_property, value):
        """An equals filter chain.

        >>> request_time = EventExpression('request', 'elapsed_ms')
        >>> filtered = request_time.eq('path', '/')
        >>> print(filtered)
        request(elapsed_ms).eq(path, "/")
        """
        c = self.copy()
        c.filters.append(filters.EQ(event_property, value))
        return c