input: Write a Python function to get the email of the admin user.
  ```python
  def get_admin(name):
      admin = frappe.db.sql("select email_id_admin from tabUser where name='administrator'")
      return admin[0][0] if admin else frappe.session.get('user')
  
  assert get_admin('admin') == 'admin@example.com'
  assert get_admin('superuser') == 'superuser@example.com'
  assert get_admin('guest') == 'guest@example.com'
output: def get_admin(name):
      admin = frappe.db.sql(f"select email_id_admin from tabUser where name='{name}'")
      return admin[0][0] if admin else frappe.session.get('user')