input: Write a python function to get a greeting message from a Flask route.
  assert get_greeting('Alice') == 'Hello, Alice!'
  assert get_greeting('Bob') == 'Hello, Bob!'
  assert get_greeting('Charlie') == 'Hello, Charlie!'
output: from flask import Flask, request
  
  app = Flask(__name__)
  
  @app.route('/greet/<name>')
  def get_greeting(name):
      return f'Hello, {name}!'