code: def get_metadata_for_ids(pmid_list, get_issns_from_nlm=False,
                           get_abstracts=False, prepend_title=False):
      
      if len(pmid_list) > 200:
          raise ValueError("Metadata query is limited to 200 PMIDs at a time.")
      params = {'db': 'pubmed',
                'retmode': 'xml',
                'id': pmid_list}
      tree = send_request(pubmed_fetch, params)
      if tree is None:
          return None
      return get_metadata_from_xml_tree(tree, get_issns_from_nlm, get_abstracts,
                                        prepend_title)
docs: Get article metadata for up to 200 PMIDs from the Pubmed database.
  
      Parameters
      ----------
      pmid_list : list of PMIDs as strings
          Can contain 1-200 PMIDs.
      get_issns_from_nlm : boolean
          Look up the full list of ISSN number for the journal associated with
          the article, which helps to match articles to CrossRef search results.
          Defaults to False, since it slows down performance.
      get_abstracts : boolean
          Indicates whether to include the Pubmed abstract in the results.
      prepend_title : boolean
          If get_abstracts is True, specifies whether the article title should
          be prepended to the abstract text.
  
      Returns
      -------
      dict of dicts
          Dictionary indexed by PMID. Each value is a dict containing the
          following fields: 'doi', 'title', 'authors', 'journal_title',
          'journal_abbrev', 'journal_nlm_id', 'issn_list', 'page'.