doctorDAlvarez

from hashlib import sha256
import json
import time

class Chain:
  def __init__(self):
    self.blockchain = []
    self.pending = []
    self.add_block(prevHash="Genesis", proof=123)

doctorDAlvarez

function useAutoScroll(ref) {
  useEffect(() => {
    const node = ref.current;
    node.scrollTop = node.scrollHeight;
  });
}

doctorDAlvarez

function useAuth() {
  const [user, setUser] = useState(null);

  useEffect(() => {
    return firebase.auth().onAuthStateChanged((user) => {
      if (user) {
        setUser({
          displayName: user.displayName,
          photoUrl: user.photoURL,
          uid: user.uid,

doctorDAlvarez

function useCollection(path, orderBy) {
  const [docs, setDocs] = useState([]);

  useEffect(() => {
    return db
      .collection(path)
      .orderBy(orderBy)
      .onSnapshot((snapshot) => {
        const docs = [];
        snapshot.forEach((doc) => {

doctorDAlvarez

import React from "react"
import FeedPost from "app/FeedPost"
import { loadFeedPosts, subscribeToNewFeedPosts } from "app/utils"

export default Feed

const PER_PAGE = 3;


function Feed() {

doctorDAlvarez

/**
 * Logs a warning in dev mode when a component switches from controlled to
 * uncontrolled, or vice versa
 *
 * A single prop should typically be used to determine whether or not a
 * component is controlled or not.
 *
 * @param controlPropValue
 * @param controlPropName
 * @param componentName

doctorDAlvarez

// Property of @dan_abramov. Very helpfull explanation of the mental model to change imperative APIs to more
// declarative custom hooks.

import React, { useState, useEffect, useRef } from 'react';

function useInterval(callback, delay) {
  const savedCallback = useRef();

  // Remember the latest callback.
  useEffect(() => {

doctorDAlvarez

import React from 'react'

function useSafeContext(customContext) {
  const context = React.useContext(customContext)
  if (!context) {
    throw new Error('You must use this context consumer hook inside a Provider')
  }
  return context
}

doctorDAlvarez

import * as React from 'react'

function useSafeDispatch(dispatch) {
  const mounted = React.useRef(false)

  React.useLayoutEffect(() => {
    mounted.current = true
    return () => {
      mounted.current = false
    }

doctorDAlvarez

import * as React from 'react'

/**
 *
 * @param {String} key The key to set in localStorage for this value
 * @param {Object} defaultValue The value to use if it is not already in localStorage
 * @param {{serialize: Function, deserialize: Function}} options The serialize and deserialize functions to use (defaults to JSON.stringify and JSON.parse respectively)
 */

function useLocalStorageState(