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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_keypair_name():
 """Returns current keypair name."""


  username = get_username()
  assert '-' not in username, "username must not contain -, change $USER"
  validate_aws_name(username)
  assert len(username) < 30  # to avoid exceeding AWS 127 char limit
  return get_prefix() + '-' + username