input: Write a python function to fetch data from an SQLite database based on a specific condition.
  assert fetch_data('<database name>', '<column name>', '<table name>', '<condition>') == [<expected result>]
  assert fetch_data('example.db', 'name', 'students', 'age > 20') == ['Alice', 'Bob']
  assert fetch_data('example.db', 'score', 'exams', 'score >= 90') == [95, 96, 100]
output: import sqlite3
  
  def fetch_data(database_name, column_name, table_name, condition):
      connection = sqlite3.connect(database_name)
      cursor = connection.cursor()
      query = f"SELECT {column_name} FROM {table_name} WHERE {condition}"
      cursor.execute(query)
      results = cursor.fetchall()
      connection.close()
      return [row[0] for row in results]