input: Write a python function to add a contact to a contact list and another function to update an existing contact in the list.
  assert contactlist == {}
  add_contact("Alice", "1234567890", "alice@example.com")
  assert contactlist == {"Alice": {"Phone": "1234567890", "Email": "alice@example.com"}}
  update_contact("Alice", "0987654321", "alice_new@example.com")
  assert contactlist == {"Alice": {"Phone": "0987654321", "Email": "alice_new@example.com"}}
  add_contact("Bob", "1112223333", "bob@example.com")
  assert contactlist == {
    "Alice": {"Phone": "0987654321", "Email": "alice_new@example.com"},
    "Bob": {"Phone": "1112223333", "Email": "bob@example.com"}
  }
  update_contact("Charlie", "4445556666", "charlie@example.com")  # Contact not found, should not change anything
  assert contactlist == {
    "Alice": {"Phone": "0987654321", "Email": "alice_new@example.com"},
    "Bob": {"Phone": "1112223333", "Email": "bob@example.com"}
  }
output: contactlist = {}
  
  def add_contact(name, phone, email):
      contactlist[name] = {"Phone": phone, "Email": email}
  
  def update_contact(name, phone, email):
      if name in contactlist:
          contactlist[name] = {"Phone": phone, "Email": email}