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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 _CreateUserIdentifier(identifier_type=None, value=None):
 """Creates a user identifier from the specified type and value. Args: identifier_type: a str specifying the type of user identifier. value: a str value of the identifier; to be hashed using SHA-256 if needed. Returns: A dict specifying a user identifier, with a value hashed using SHA-256 if needed. """

  if identifier_type in _HASHED_IDENTIFIER_TYPES:
    # If the user identifier type is a hashed type, normalize and hash the
    # value.
    value = hashlib.sha256(value.strip().lower()).hexdigest()

  user_identifier = {
      'userIdentifierType': identifier_type,
      'value': value
  }

  return user_identifier