system: You are a contract-analysis assistant performing a span-extraction task. You are given an excerpt from a commercial contract and the name of a clause type to locate within it.

Return the exact text of the requested clause, copied verbatim from the excerpt — identical wording and punctuation, with no paraphrasing, summarising, explanation, or added commentary.

The excerpt is one window of a much longer contract and often will not contain the requested clause. If the requested clause does not appear in this excerpt, respond with exactly: Not found.

Output only the extracted clause text, or the exact string `Not found.` — nothing else.

user: Contract excerpt:
"""
appropriate execution of the same. All future or present obligations resulting from the relations of the Parties with its personnel shall be exclusively borne by the Party involved, and therefore, each Party assumes full responsibility concerning compliance with labor regulations and social security and shall hold the other Party harmless against any claim in connection with any violation to the mentioned regulations. CLAUSE TWENTY-SECOND INDEMNITY 22.1 ECOPETROL is obliged to protect, indemnify and hold the SENDER harmless against any loss, cost or damage to be caused or derived from, or related with the breaching of the Contract by ECOPETROL, save the same are caused by Excusable Events. 22.2 The SENDER is obliged to protect, indemnify and hold ECOPETROL harmless and its parent, affiliates and subsidiaries, and the directors, employees, agents and representatives of ECOPETROL, and of its affiliates and subsidiaries against any loss, cost or damage to be caused or derived from or related with the execution of the Contract, except (i) by causes exclusively attributable to ECOPETROL or (ii) force majeure or unforeseen circumstances and acts of third parties. CLAUSE TWENTY-THIRD CONFIDENTIALITY 23.1 The Parties make the commitment to keep strict confidentiality and not to disclose to any person any information considered as confidential (the "Information"), which has been provided through the development of the Contract hereof, and through the development of the activities inherent to ECOPETROL and/or the SENDER. 23.2 Without prejudice of the foregoing, only in the following cases information may be disclosed: 23.3 For any information to be disclosed, that must be or wished to be disclosed as established in previous numerals, only the disclosure in question shall proceed after consulting, if the period granted by law or the authority ordaining the disclosure of the information allows it, with the Party that has provided the information. a) When the disclosure of information is mandatory by law; b) When the disclosure of information is ordered by a competent authority; c) When the information in question is of public domain, without any action or omission from the Parties; or d) When the entity providing the information authorizes it, in each case, previously and in writing; 12 23.4 Furthermore, it shall be understood that the Information may be disclosed to employees, advisors and officers of the Parties, as well as employees, advisors, officers, auditors and insurance companies of the shareholders of ECOPETROL or the SENDER (including parents, affiliates and subordinates). 23.5 In any case, the Parties shall ensure that persons to whom the Information is disclosed hold, in turn, said Information as confidential and refrain from disclosing it. The Parties shall be responsible for any disclosure of Information to any of its employees, advisors and officers. If the Parties become aware of any unauthorized disclosure of confidential Information, it shall be notified immediately to the other Party and jointly shall take all measures necessary and/or convenient to prevent other disclosures of Information in the future. 23.6 The SENDER shall solely use or permit the use of the Confidential Information disclosed under the execution of this Contract to perform it. The disclosure of Confidential Information under this Contract shall not grant any other right. 23.7 The SENDER shall be responsible for ensuring that all persons to whom the Confidential Information is revealed under the execution of this Contract maintain said Information as Confidential and without disclosing it to any unauthorized persons. The SENDER shall be liable for any damage caused to ECOPETROL in case of breaching the Contract hereto, or if through negligent actions or omissions, discloses or makes public any Confidential Information outside the terms set out herein in accordance with law. 23.8 ECOPETROL may request the return of the Information at any time after notifying in writing to the other Party. Within thirty (30) days following the reception of said notification, the SENDER shall return all original Information and destroy or make to be destroyed all copies and reproductions (in any manner, including but without being limited to electronic means) in its possession and in possession of persons to whom it was disclosed pursuant with the Contract hereof. In any case, upon expiration of the term of execution of the Contract, the SENDER shall return all original Information and destroy or make to be destroyed all copies and reproductions (in any manner, including but without being limited to electronic means) in its possession and in possession of persons to whom it was disclosed pursuant with the Contract hereof. 23.9 During the term of execution of the Contract, ECOPETROL
"""

Extract the exact clause related to "Anti-Assignment" from the excerpt above.