input: Write a python function to send a GraphQL query using the requests library and return the JSON response.
  assert send_graphql_query('http://localhost:4000', {"query": "{ user(id: 2) { name age address { street city } } }"}) == {'data': {'user': {'name': 'John', 'age': 30, 'address': {'street': '123 Main St', 'city': 'Anytown'}}}}
  assert send_graphql_query('http://localhost:4000', {"query": "{ user(id: 3) { name age address { street city } } }"}) == {'data': {'user': {'name': 'Jane', 'age': 25, 'address': {'street': '456 Elm St', 'city': 'Othertown'}}}}
output: import requests
  
  def send_graphql_query(url, query):
      headers = {"Content-Type": "application/json"}
      response = requests.post(url, json=query, headers=headers)
      return response.json()