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:
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shall be deemed to be required to be taken on the next occurring Business Day. 15.17 Translations. This Agreement is in the English language only, which language shall be controlling in all respects, and all versions hereof in any other language shall be for accommodation only and shall not be binding upon the Parties. All communications and notices to be made or given pursuant to this Agreement, and any dispute proceeding related to or arising hereunder, shall be in the English language. If there is a discrepancy between any translation of this Agreement and this Agreement, this Agreement shall prevail. 80 Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020 15.18 Further Actions. Each Party agrees to execute, acknowledge and deliver such further instruments, and to do all such other acts, as necessary or appropriate in order to carry out the purposes and intent of this Agreement. 15.19 Counterparts. This Agreement may be executed in two or more counterparts by original signature, facsimile or PDF files, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] 81 Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020 IN WITNESS WHEREOF, the Parties intending to be bound have caused this Collaborative Research, Development and Commercialization Agreement to be executed by their duly authorized representatives as of the Effective Date. Revolution Medicines, Inc. Aventis, Inc. By: /s/ Mark A. Goldsmith, M.D., Ph.D. By: /s/ Douglas J. McCormack Name: Mark A. Goldsmith, M.D., Ph.D. Name: Douglas J. McCormack Title: President & Chief Executive Officer Title: Vice President Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020 Aventis, Inc. c/o Sanofi 50 Binney Street Cambridge, MA 02142 August 24, 2018 Revolution Medicines, Inc. 700 Saginaw Dr. Redwood City, CA 94063 Attention: General Counsel Re: Amendment to Collaborative Research, Development and Commercialization Agreement Dear Revolution Medicines, Inc.: Reference is hereby made to that certain Collaborative Research, Development and Commercialization Agreement (the "Collaboration Agreement"), dated as of June 8, 2018, by and between Revolution Medicines, Inc. ("RevMed") and Aventis, Inc. ("Sanofi"). Capitalized terms used but not defined in this letter agreement (this "Letter") shall have the meanings assigned to them in the Collaboration Agreement. Each of RevMed and Sanofi acknowledges and agrees as follows: 1. Amendment to Section 6.5 of the Collaboration Agreement. The first sentence of Section 6.5 of the Collaboration Agreement is hereby amended and restated in its entirety as follows: "Following the Effective Date, but in any case prior to the Initiation of the first Clinical Trial sponsored by Sanofi for a Product, the Parties shall enter into a pharmacovigilance agreement setting forth the worldwide pharmacovigilance procedures for the Parties with respect to the Products, such as safety data sharing, adverse events reporting and safety profile monitoring (the "Pharmacovigilance Agreement")." 2. No Other Amendments. This Letter shall be deemed to be a part of and incorporated into the Collaboration Agreement. In the event of a conflict between this Letter and the Collaboration Agreement, this Letter shall control. Except as expressly set forth in this Letter, all of the terms and conditions of the Collaboration Agreement shall remain unchanged and are ratified and confirmed in all respects and remain in full force and effect. 3. Entire Agreement. This Letter, together with the Collaboration Agreement and any exhibits or attachments thereto (including, without limitation, the Correspondence and the Exhibits thereto), constitutes the entire agreement between the Parties regarding the subject matter hereof, and any reference to the Collaboration Agreement shall refer to the Collaboration Agreement, as amended by this Letter. 4. Counterparts. This Letter may be executed in one (1) or more counterparts, each of which will be deemed an original, but all of which together will constitute one and the same instrument. Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020 5. Governing Law. This Letter shall be governed by and construed in accordance with the laws of the State of New York without reference to any rules of conflict of laws. [Remainder of Page Intentionally Left Blank] Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020 Please indicate your agreement by countersigning in the space provided below and returning a copy to my attention. Sincerely, Aventis, Inc. By: /s/ Douglas J. McCormack Name: Douglas J. McCormack Title: Vice President Acknowledged and Agreed: Revolution Medicines, Inc. By: /s/ Mark A. Goldsmith Name: Mark A. Goldsmith Title: Chief Executive Officer [Signature Page to Letter Agreement] Source: REVOLUTION MEDICINES, INC., S-1, 1/17/2020
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Extract the exact clause related to "Effective Date" from the excerpt above.

assistant: June 8, 2018