input: def fetch_json_from_sql(database_name: str, table_name: str) -> json:
      """
      Fetches data from an SQL database and presents the data in the form of a JSON. 
      The function connects to the specified SQLite database, retrieves all records 
      from the specified table, and returns them as a JSON object.
      
      >>> fetch_json_from_sql('database.db', 'users')
      [{"id": 1, "name": "John Doe", "age": 30}, {"id": 2, "name": "Jane Doe", "age": 25}]
      """
output:     import sqlite3
      import json
  
      conn = sqlite3.connect(database_name)
      cursor = conn.cursor()
      cursor.execute(f"SELECT * FROM {table_name}")
      rows = cursor.fetchall()
      columns = [description[0] for description in cursor.description]
      result = [dict(zip(columns, row)) for row in rows]
      conn.close()
      return json.dumps(result)