input: Write a python function to send an SMS message using AWS SNS.
  assert send_sms('+1234567890', 'Hello World')['statusCode'] == 200
  assert send_sms('+1987654321', 'Testing AWS SNS')['statusCode'] == 200
output: import boto3
  from botocore.exceptions import BotoCoreError, ClientError
  
  def send_sms(phone_number, message):
      sns_client = boto3.client('sns', region_name='us-east-1')
      
      try:
          response = sns_client.publish(
              PhoneNumber=phone_number,
              Message=message
          )
          return {'statusCode': 200, 'messageId': response.get('MessageId')}
      except (BotoCoreError, ClientError) as error:
          return {'statusCode': 400, 'error': str(error)}