input: Write a python function to parse an email from a file using the email module and return the message as a string.
  assert parse_email('sample_email.eml') == 'Expected email content as string'
  assert parse_email('another_email.eml') == 'Another expected email content as string'
output: import email
  
  def parse_email(file_path):
      with open(file_path, 'r') as file:
          msg = email.message_from_file(file)
          return msg.get_payload()