At any time during which any custodian is in custody or control of any documentary material, tangible things, reports, answers to questions, or transcripts of oral testimony given by any person in compliance with any civil investigative demand, such person may file, in the district court of the United States for the judicial district within which the office of such custodian is situated, and serve upon such custodian, a petition for an order of such court requiring the performance by such custodian of any duty imposed upon him by this section or section
57b–2 of this title.